Answer:
y = 12
Explanation:
The first step is to determine the perimeter of triangle TUV. We know side UV has a length of 20 cm and that the triangle is equilateral, so all sides have the same length. Thus the perimeter of the triangle must be 20 cm * 3 = 60 cm
The perimeter of PQRS is the sum of the lengths of sides PQ, QR, RS, and SP in cm.
PQ = y + 6
QR = 9 (given in diagram)
RS = 2y
SP = 9 (the diagram shows that it has the same length as QR)
Together they must add up to 60 cm to match the perimeter of the triangle, so:
PQ + QR + RS + SP = 60
(y + 6) + 9 + 2y + 9 = 60
3y + 24 = 60
3y = 36
y = 12