Question

What is the value of X

Answer 1

88 i believe is right
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Answer 2

Suppose that a polygon has ‘n’ sides, then it is to be divided into (n - 2) triangles. 

We know that, the sum of the interior angles of a triangle = 180°.

Therefore, the sum of the angles of (n - 2) triangles = 180 × (n - 2)

                                                                            = 2 × 90 × (n - 2)

                                                                            = 2 right angles × (n – 2)

                                                                            = 2(n – 2) right angles

                                                                            = (2n – 4) right angles

Therefore, 

the sum of interior angles of a polygon having n sides is (2n – 4) right angles.

Hence,

the sum of the interior angles of a pentagon (n = 5)

= (2n - 4) right angles

= (2 × 5 - 4) × 90°

= (10 - 4) × 90°

= 6 × 90°

= 540°

131 + 108 + 107 + 110 + x = 540

456 + x = 540

x = 540 - 456

x = 84°