Answer:
QR = 5
Step-by-step explanation:
Since the parallelograms are similar, then the ratios of corresponding sides are equal, that is
[tex]\frac{AB}{PQ}[/tex] = [tex]\frac{BC}{QR}[/tex], then
[tex]\frac{9}{3}[/tex] = [tex]\frac{15}{QR}[/tex] ( cross- multiply )
9QR = 45 ( divide both sides by 9 )
QR = 5