Answer:
c. 24
Explanation:
Triangle PQR has dimensions that are a factor of 45/15 = 3 times those of triangle ABC, so side QR will be 3 times the length of side BC:
3·8 = 24 . . . . . matches choice C
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We are not given any information that says the triangles are similar. We have assumed they are. Without that information, there is no basis for working the problem.