By Segment Addition Postulate,

PQ+QR=PR

Substitute given expressions:

(8y+5)+QR=13y+25

Subtract 8y8y from both sides:

5+QR=5y+25

Subtract 5 from both sides:

QR=5y+20

PQ+QR=PR

Substitute given expressions:

(8y+5)+QR=13y+25

Subtract 8y8y from both sides:

5+QR=5y+25

Subtract 5 from both sides:

QR=5y+20