Step-by-step explanation: First I though, if they stoppedd for lunch at 1:20 and they've been doing yard work for 1 hour and 35 minutes, I would subtract. 1 hour taken away from 1:20 would be 12:20. Then, since it would be hard to subtract 35 minutes from 12:20, 35 minutes - 20 minutes = 15 minutes. 12:20 subtract 20 minutes = 12:00. 12:00 - 15 minutes equal to 11:45. I hope this helps. I know this explanation can be confusing but it's the best I can do at the moment.
