Skip to the main content
PeabodyMake a free story

🧩 8th grade math · Patterns & Algebra

Two equations at once

The solution of a system is the point where the two lines cross. It makes both equations true. Read across to find x, then up or down to find y. Left of the y-axis and below the x-axis are negative.

Worked example

The two lines are the graphs of two equations, and they cross at one point.
What is the x-coordinate of the solution?
βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
Answer: x = 1
The solution is where the two lines cross: the point (1, 2). The x-coordinate is 1.

For grown-ups: Systems of two linear equations. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.

  • CCSS 8.EE.C.8
What this practises, for teachers

Practices systems of two linear equations (8.EE.C.8). A printable sheet with its answer key, worked answers on the page, no accounts.

β–Ά Practise it

For your class

πŸ–¨οΈ Printable sheet and key

On the board with this skill:

Try three

  1. The two lines are the graphs of two equations, and they cross at one point.
    What is the y-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
    Show the answer and how
    Answer: y = 5
    The solution is where the two lines cross: the point (1, 5). The y-coordinate is 5.
  2. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
    Show the answer and how
    Answer: x = 3
    The solution is where the two lines cross: the point (3, 1). The x-coordinate is 3.
  3. The two lines cross at one point. Which ordered pair (x, y) is the solution of the system?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
    Show the answer and how
    Answer: (1, βˆ’2)
    The solution of a system is the point where the lines cross. Here they cross at (1, βˆ’2). Check it in both equations. Answer: (1, βˆ’2).

Before and after

Learn first: Multi-step equations (8th)

Comes next: High school algebra (HS)

Name: ____________________Date: ____________Score: ____ / 12

Two equations at once (8th grade)

  1. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  2. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  3. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  4. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  5. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  6. The two lines are the graphs of two equations, and they cross at one point.
    What is the y-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  7. The two lines are the graphs of two equations, and they cross at one point.
    What is the y-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  8. The two lines are the graphs of two equations, and they cross at one point.
    What is the y-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  9. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  10. The two lines are the graphs of two equations, and they cross at one point.
    What is the y-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  11. The two lines are the graphs of two equations, and they cross at one point.
    What is the x-coordinate of the solution?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line
  12. The two lines cross at one point. Which ordered pair (x, y) is the solution of the system?
    βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456βˆ’6βˆ’5βˆ’4βˆ’3βˆ’2βˆ’1123456Blue lineRed line

Answer key

  1. x = 4
  2. x = 3
  3. x = 3
  4. x = 1
  5. x = 2
  6. y = 3
  7. y = -2
  8. y = 4
  9. x = 1
  10. y = 2
  11. x = -1
  12. (1, βˆ’3)

More 8th grade skills: all 8th grade math skills, or every grade at math skills.