Answer: 54 minutes
Step-by-step explanation: Given that Tom spent 1/10 hour less time than normal exercising.
Let the normal exercising hour = H
Tom spent 1/10 hour less time than normal exercisin. That is
Tom spent = H - 1/10H
Tom spent = 9/10 hours
The much time Tom spent exercising last week will be
9/10 × 60 = 54 minutes