6. A building project takes 12 men 54 days to complete.
(i) How long will it take 9 men to finish the same project?
(ii) Given that the project must be completed in 36 days, find how many men are needed.

7. A shop employs one man and one woman as shop assistants. the man works for 10 hours a day and the woman works for 8 hours per day, and their wages per hour are in the ratio 7:5.If the woman receives $24 per day, find the man's daily wage.

8. To paint a house, John stairs 6 days, Peter takes 4 days, and Paul takes 12 days. How many days will they take if they work together?