Question

Larry can clear his driveway of a foot of snow in 1 hour and 45 minutes, and Donald can complete the same job in 1 hour and 10 minutes. About how long will it take them together to clear the driveway?

Answer 1

We are given

Larry can clear his driveway of a foot of snow in 1 hour and 45 minutes

we know that

1 hour =60 min

so, Larry can clear his driveway of a foot of snow in 60+45=105 min

So, in 1 min , Larry can do

$=\frac{1}{105}$

Donald can complete the same job in 1 hour and 10 minutes.

we know that

1 hour =60 min

so, Donald can complete the same job in  60+10=70 min

So, in 1 min , Donald can do

$=\frac{1}{70}$

Total work by them in 1 min is

$=\frac{1}{105}+\frac{1}{70}$

$=\frac{1}{42}$

So, time taken by them when they work together is

$=42min$............Answer