All three sides of the triangle are the same length because all three angles are the same (all three angles are 60 degrees). How do I know this? The angle markers visually indicate the angles are the same. If x is the angle then x+x+x = 180 leads to 3x = 180 and it solves to x = 60, which is the measure of each angle. This is an equilateral triangle.
VT = ST
5r+8 = 9r
8 = 9r-5r
8 = 4r
4r = 8
r = 8/4
r = 2
If r =2, then 9*r = 9*2 = 18 which is the length of each side
SV is 18 units long. You have the correct answer.
