Question 286942
Hint: Let 'y' be the vertex angle. Recall that the angles in a triangle add to 180 degrees. So {{{(8x-7)+(6x+9)+y=180}}}. Also, since we're dealing with an isosceles triangle, this means that the base angles are equal. This means that {{{8x-7=6x+9}}}. Solve this equation for 'x' and then use that solution to find 'y'.