Question

Question #ab1f4

Answer 1

`1/3` of the job

Explanation:

If it takes to `21` hours to finish the job `(100%)`, let `J` be the job. Then,

`21=100%J=1J`

or

`7=(1-:3)=1/3J`

So `1/3` of the job is done in `7` hours.