This is a polygon. i need finding the missing angle ?

First find how much the sum of interior angles measure:

180(n-2)

(n is the number of sides)

180 (5 - 2)
180 (3)
540

Now add all the angles and set them equal to 540.

87 + 105 + 135 + 92 + x = 540
419 + x = 540
x = 121

Hope this helps :)