Question

Question #f19cb

Answer 1

The time it would take for Jack and Marilyn to mow the lawn​ together will be `2`hours and `55` minutes.

Explanation:

Jack mows the lawn in `5` hours.

That means Jack mows `1/5` th of the lawn in `1` hour.

Similarly,

Marilyn can mow the same lawn in `7`hours.

That means, Marilyn mows `1/7` th of the lawn in `1` hour.

So if they work together,

In 1 hour they will mow `1/5 +1/7` th of the lawn, i.e.:

`=1/5(7/7) + 1/7(5/5)`

`= 7/35+5/35 = 12/35`th of the lawn is mowed in `1` hour.

That means, they will need `35/12` hours to mow the lawn together,i.e.:

`35/12 = 2 11/12` hours.

`11/12`th of an hour =`11/12 x 60` minutes= `55` minutes.

The time it would take for Jack and Marilyn to mow the lawn​ together will be `2`hours and `55` minutes.

Answer 2

`2hrs` `55 minutes`

Explanation:

In `5` hrs Jack mows `1` Lawn
So in `1` hr Jack mows `1/5` Lawn

In `7` hrs Marilyn mows `1` Lawn
So in `1` hr Marilyn mows `1/7` Lawn

So we can write together Jack and Marilyn in `1` hr can mow `1/5+1/7=(7+5)/35=12/35` Lawn

So they can mow a Lawn i.e. `1` Lawn in `35/12 hrs=2 11/12hrs`=`2hrs` `55 minutes`