an isosceles triangle means two sides are the same and the bottom two angles are the same length. So you would equal the two equations and solve it to get x. Then replace one of the equation's x with the number you got, which would be 5, and solve that. Since both bottom angle are the same, the other angle would be the same degree, 37*. A triangle is 180* total, so subtract that by two 37's and you'll get the answer.