Question 474679
Since it is an isosceles triangle, two of the sides are equal which means that the third side is 7 or 15.
If the third side is 7, then you cannot form a triangle from these three sides of 7, 7, and 15 because the base of an isosceles triangle must be shorter than the sum of the lengths of the two equal sides.
Therefore, the third side must be 15 and the perimeter is 7+15+15 = 37.