Answer:
x = 7
Explanation:
In a trapezoid
each lower base angle is supplementary to the upper base angle on the same side , then
∠ S + ∠ V = 180
8x - 21 + 145 = 180
8x + 124 = 180 ( subtract 124 from both sides )
8x = 56 ( divide both sides by 8 )
x = 7