Madelynne hopped 12 times in 15 seconds. What is her speed in hops per minute?

60 seconds = 1 minute

60/15 = 4

12 hops in 15 seconds is the same as

4 * 12 hops in 4 * 15 seconds, or

48 hops in 60 seconds, and since 60 sec = 1 min, it equals

48 hops per minute.