A man took a loan of 90,000 naira without interest for a cooperative society and he is to be paying back 2,500 naira on monthly installment. how many years will it take him to finish paying the debt?

It will take the man 3 years to finish paying the debt.

Here's the calculation:

To find out how many months it will take him to pay back the loan, we divide the total loan amount by the monthly installment:

90,000 ÷ 2,500 = 36

So, he will make 36 monthly payments of 2,500 naira each.

To convert this to years, we divide the number of months by 12:

36 ÷ 12 = 3

Therefore, it will take him 3 years to finish paying back the debt.