Solve for the value of s.
Since the sum of the angles in this are supposed to be 180o and that one of the angles is 90o, we can use a bit of algebra to find the answer.
4s + 8 = 180 - (54 + 90)
4s + 8 = 180 -144
4s + 8 = 36
4s = 28
s = 7
