Question

Twin brothers,billy and Bobby, can mow their grandparents lawn together in 72 minutes. Billy could mow the lawn by himself in 15 minutes less time that it would take Bobby. How long will it take Bobby to mow the lawn by himself?

Answer 1

Billy used 28 mins 30 sec to mow the lawn and Bobby used 43 mins 30 sec to now the lawn both within 72 mins

Explanation:

let x represent Billy

let x+15 represent Bobby

x + x + 15 = 72

2x = 72 - 15

2x = 57

2x/2 = 57/2

x = 28.5 minutes = 28 minutes 30 seconds

Bobby = x + 15

= 28.5 + 15

= 43.5 minutes= 43 minutes 30 seconds