Question

85,110,x,120,120 : find the value of x

Answer 1

540 degrees in a pentagon

110 + 120+ 120 + 85 = 435

540 - 435 = 105

Answer 2

The sum of angles of a pentagon is 540°, so x must be chosen to make that so.

85 + 110 + x + 120 + 120 = 540

540 -435 = x = 105

_____

The formula usually used to find the degree measure of the internal angles of an n-sided polygon is (n -2)·180°. For n=5, this is 3·180° = 540°.