StudyBrixFree worksheets, study guides and courses

Mathematics · Grades 9–11

Simultaneous equations

Add the equations to eliminate y, then solve for x.

Make a worksheet

The key idea

Add the equations to eliminate y, then solve for x.

x + y = s; x − y = d → x = (s + d)/2

Worked examples

Solve for x: x + y = 39 and x − y = 11.

2x = 50 → x = 25

25

Solve for x: x + y = 32 and x − y = 20.

2x = 52 → x = 26

26

Try it yourself

  1. Solve for x: x + y = 25 and x − y = 7.

  2. Solve for x: x + y = 20 and x − y = -2.

Check your understanding

Answers and marking notes
  1. 16

    2x = 32 → x = 16

  2. 9

    2x = 18 → x = 9

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.