Question

During the summer holidays, your brother earns extra money mowing lawns. He mows 6 lawns an hour and has 21 lawns to mow. How long will it take him?

Answer 1

His brother will take 3.5 hours or
`3(1)/(2)` hours to mow 21 lawns

Explanation:

Given:

His brother mows 6 lawns in an hour.

To find the time his brother takes to mow 21 lawns.

Solution:

We will unitary method to find the time he will take to mow 21 lawns.

If 6 lawns are mowed in 1 hour

So, 1 lawn will me mowed in =
`(1)/(6)` hours.

Thus 21 lawns will be mowed in =
`(1)/(6)* 21=(21)/(6)=3.5` hours.

Thus, his brother will take 3.5 hours or
`3(1)/(2)` hours to mow 21 lawns