Question

Jack usually mows his lawn in 5 hours. Marilyn can mow the same yard in 3 hours. How much time would it take for them to mow the lawn​ together?

Answer 1

1.875hours

Explanation:

First, remember that `Q=(quantity)=r(rate)xxt(time)`

From this, we can set up a table:

From this, we know that `1/5+1/3=1/t`

To solve this, we find the LCM of 5,3, and t.
The LCM of 5,3,and t is 15t.

We turn the fraction in the equatoin so they all have the denominator of 15t.

`1/5+1/3=1/t` becomes
`(3t)/(15t)+(5t)/(15t)=15/(15t)`
`(3t+5t)/(15t)=15/(15t)`
`(8t)/(15t)=15/(15t)`
`120t^2=225t`
`120t=225`
`t=15/8`

Therefore, together, it takes 1.875 hours to mow the lawn.