Answer:
Judy spent 55 minutes exercising
Step-by-step explanation:
Here, we want to know the amount of time Judy spent exercising.
We proceed as follows;
Mary spent 3 hours , sandy spent 50 minutes less than Mary. The amount of time spent by Sandy is thus 2hrs 10 minutes
Judy spent 1hr 15 min less, the amount of time he spent is thus
2hrs 10 minutes - 1 hr 15 min
2 hrs 10 minutes is same as 2(60) + 10 = 120 + 10 = 130 minutes
I hr 15 minutes = 60 + 15 = 75 minutes
The amount of time spent is thus 130 - 75 = 55 minutes