Answer:
SR = 28
Explanation:
Recall: The corresponding side lengths of any two similar polygons are proportional.
Since the two polygons given are similar, it implies that:
SR/DC = PQ/AB
SR = ?
DC = 20
PQ = 21
AB = 15
Plug in the values
SR/20 = 21/15
Solve for SR. Cross multiply
SR*15 = 21*20
SR*15 = 420
Divide both sides by 15
SR = 420/15
SR = 28