Answer:
19
Step-by-step explanation:
The opposite sides are equal, so:
PS = 3y+1
RS = 4y+2
QR = 3y+1
PQ = 4y+2
Therefore, we can set the perimeter 90 = PS+RS+QR+PQ
90 = (3y+1) + (4y+2) + (3y+1) + (4y+2), or,
90 = 2(3y+1) + 2(4y+2)
90 = 6y+2 + 8y+4
90 = 14y + 6
84 = 14y
y = 6
Then, we go back to the question. It's asking for the length of PS. PS = 3y+1, so we plug in 6 for y
3(6)+1
18 + 1 = 19
