Answer:
x = 54
Step-by-step explanation:
The angles of a triangle add up to 180.
This is an isosceles triangle so the angles at the base of the 2 congruent sides are equal.
One of the angles at the bottom is 63 deg. so the other one is 63 too.
We solve for x knowing the first fact.
x = 180 - (63 + 63) = 54
