Answer:
x=5
Step-by-step explanation:
since the 2 base angles are the same, we can assume that the sides opposite to them are equal, meaning that this is an isosceles triangle:
5x-8=2x+7
3x=15
x=5
(if u need more help on how i solved for x just ask in the comments, i will try my best to help)
hope this helped a bunch, brainliest plz! :)