A man monthly salary is 12,000, 1/4 of the salary is spent on rent. Out of the remainder, 2/5 is spent on food, and 1/8 on transport. How much has he left?

Answer 1

salary ---- 12,000
spent on rent = (1/4)(12000) = 3,000
leaving 9000
spent on food = (2/5)(9000) = 3600
spent on transp = (1/8)(9000) = 1125
leaving 9000 - (3600+1125) = 4275

or
amount spent on food + transp = 2/5 + 1/8 = 21/40
amount left = 12000(1 - 1/4)(1 - 21/40) = 4275