Bob atarted mowing at 9:55am It took him 25 minutes to mow the front yard and 45 minutes to mow the back yard. At what time did Bob finish mowing?

So bob started at 9:55. you add the 25 minutes from how it took him to mow the front yard to your starting time

9:55 there are sixty minutes in an hour

+:25

10:20 am

then you add the 45 minutes it took him to mow the back yard from that time

10:20 remember there are only sixty minutes in an hour

+ : 45

11:05 am

so Bob finished mowing at 11:05am