Find the vertex angle of an isosceles triangle with base angles of (3x+10) and (8x-15). Show your work for credit.
So the two base angles must be equal
8x - 15 = 3x + 10
5x = 25
x = 5
so each of the base angles is 25°
That would leave 130° for your vertex angle
(25+25+130=180)