Answer:
x = 8
Step-by-step explanation:
Well, you didn't specify if it was an isosceles triangle or if it was equal or anything so we're going to assume it is.
So since both sides are equal 7+x=15
7(-7)+x=15(-7)
x=8
Plug in 8 as x to check
7 + 8
15
Which would equal the other side.
