human
Pete walks backwards three times faster than Susan walks forwards, and Tracy does one-handed cartwheels twice as fast as Susan walks forwards. But Pete can walk on his hands only one quarter the speed that Tracy can do cartwheels. If Pete walks on his hands at 2 miles per hour, how fast can Pete walk backwards, in miles per hour?
assistant
How fast can Tracy do 1-handed cartwheels? ** If Pete walks on hands at 1/4 what Tracy can do 1-handed cartwheels, then Tracy can do 1-handed cartwheels at 2*4=8 miles per hour.
How fast does Susan walk? ** Since Tracy does 1-handed cartwheels twice the rate of Susan's forward walking, then Susan walks at 8/2=<<8/2=4>>4 miles per hour.
How fast does Pete walk backwards? ** Pete walks backwards 3x faster than Susan walks forward, and thus Pete walks backwards at 4*3=12 miles per hour.
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