Answer:
9
Step-by-step explanation:
the 2 angles create a right angle ( indicated by the little square.)
right angles have a measure of 90 degrees
hence, 90 = 72 + 2x
( note that we just created an equation that we can use to solve for x )
we now solve for x using the equation we created.
90 = 72 + 2x
step 1 subtract 72 from each side
90 - 72 = 18
72 - 72 cancels out
we now have 18 = 2x
step 2 divide each side by 2
18 / 2 = 9
2x / 2 = x
we're left with x = 9
