Question

8. If 7 men can do a piece of work in 9 days, how long would 21 men take to do it​

Answer 1

Answer: 3 days

step-by-step explanation: time taken by 7 men's to complete the work = 9 days

now

time taken by one man to complete the work = 63

therefore

time taken by 21 men to complete the work = 63/21

                                                                              = 3 days