A group of workers promised to finish a job in 18 days, but 6 of them went on leave, so the rest took 20 days to finish it. How many workers were there at first?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 60
The job is the same, so the total worker-days stay the same: workers \(\times\) days before the change equals workers \(\times\) days after it.
Let there be \(N\) workers at first
\(18N=20(N-6)\)
\(18N=20N-120\), so \(2N=120\)
\(N=60\)