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Solve for x: co-interior angles

Year 9 maths · Fieldbook Learning

Name ______________________ Date __________

Write an equation from the angle relationship: equal angles are set equal, co-interior angles add to 180°. Then solve for x.

  1. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 15)° and (4x + 3)°. Find x.
  2. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x − 2)° and (3x + 46)°. Find x.
  3. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 1)° and (5x + 59)°. Find x.
  4. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x)° and (3x + 60)°. Find x.
  5. Two parallel lines are cut by a transversal. Two co-interior angles measure (x + 17)° and (5x + 43)°. Find x.
  6. Two parallel lines are cut by a transversal. Two co-interior angles measure (2x)° and (4x + 48)°. Find x.
  7. Two parallel lines are cut by a transversal. Two co-interior angles measure (3x − 6)° and (5x − 6)°. Find x.
  8. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 16)° and (5x + 34)°. Find x.
  9. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 11)° and (5x − 31)°. Find x.
  10. Two parallel lines are cut by a transversal. Two co-interior angles measure (x − 1)° and (4x + 46)°. Find x.
  11. Two parallel lines are cut by a transversal. Two co-interior angles measure (2x + 5)° and (2x + 59)°. Find x.
  12. Two parallel lines are cut by a transversal. Two co-interior angles measure (x + 3)° and (4x + 32)°. Find x.
  13. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 6)° and (4x + 12)°. Find x.
  14. Two parallel lines are cut by a transversal. Two co-interior angles measure (x + 13)° and (5x − 37)°. Find x.
  15. Two parallel lines are cut by a transversal. Two co-interior angles measure (3x + 13)° and (4x − 57)°. Find x.
  16. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 11)° and (2x + 57)°. Find x.
  17. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x − 5)° and (2x + 3)°. Find x.
  18. Two parallel lines are cut by a transversal. Two co-interior angles measure (3x − 1)° and (3x + 31)°. Find x.
  19. Two parallel lines are cut by a transversal. Two co-interior angles measure (2x − 8)° and (x + 41)°. Find x.
  20. Two parallel lines are cut by a transversal. Two co-interior angles measure (5x + 16)° and (2x + 31)°. Find x.
More free practice: fieldbooklearning.com/uk/practice/year-9/solve-for-x-co-interior-angles/

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Answer key: Solve for x: co-interior angles

  1. 18
  2. 17
  3. 12
  4. 15
  5. 20
  6. 22
  7. 24
  8. 13
  9. 20
  10. 27
  11. 29
  12. 29
  13. 18
  14. 34
  15. 32
  16. 16
  17. 26
  18. 25
  19. 49
  20. 19