1. Four pumps can fill a tank in 42 minutes
How long will 6 pumps at the same kind fill a tank?

2. Romeo, who works 8 hours a day, can finish a job in 25 days. How many hours a day must he work

3. Eight farmers can plant rice in 3 hectares for 9 days. At the same rate, how long will farmers finish the same job?

4. Three secretaries can finish a typing job in 12 hours, How long will it take 4 secretaries to do the job at the same rate?

5. If 4 farmers can plough a field in 9 days how long can 6 farmers do it?

(cancellation method) Explanation needed​