Question

Mr Singh spends 1/4 of his monthly salary on the repayment of a housing loan. Of the remainder, he spends 1/5 on food and the PUB bill, and puts aside 1/10 for transport costs. This leaves him with $630 a month. What is his monthly salary?

Answer 1

Mr Singh spends 1/4 of his monthly salary on the repayment of a housing loan. Of the remainder, he spends 1/5 on food and the PUB bill, and puts aside 1/10 for transport costs. This leaves him with 630 a month. What is his monthly salary?

Solution.

We first find which part of salary stays after all payments

$1-\frac{1}{4}-(1-\frac{1}{4})(\frac{1}{5}+\frac{1}{10})=\frac{3}{4}-\frac{3}{4}\frac{3}{10}=\frac{21}{40}$

Then his monthly salary is

$630\frac{40}{21}=1200$

Answer. 1200.