Four interior angles of a pentagon are 90°- x°, 90°+ x°, 110°- 2x°, 110°+ 2x°. Find the fifth interior angle

  • A 110°
  • B 120°
  • C 130°
  • D 140°
jamb 1988mathematics

The correct answer is D. 140°

A pentagon has five sides, and the sum of its interior angles is (5-2)180 = 540 degrees. The sum of the four given angles is 90-x + 90+x + 110-2x + 110+2x = 400 degrees. So, the fifth angle is 540 - 400 = 140 degrees.

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