if jack can mow his lawn in 4 hours and sue can mow the same lawn in 7 hrs how much time if they both mowed the lawn together???

Answer 1

Jack's rate = 1/4
Sue's rte = 1/7
combined rate = 1/4 + 1/7 = 11/28

combined time = 1/(11/28) = 28/11 = 2.5454..
or 2 hrs, 33 minutes (appr for minutes)

Answer 2

Thanks for showing me.