Answer: 15
Step-by-step explanation:
It's an Isosceles triangle meaning both sides are congruent (same)
So with that in mind we can make an equation making them equal to each other to find X.
3x = 5x - 30
Subtract 5x from both sides
-2x = -30
We can't have a negative x so we divide x by a negative
x = 15
