Question

A man spends $\frac{2}{5}$ of his salary on food and $\frac{3}{10}$ of the remaining on house rent, electricity, etc. What fraction of his salary is still left with him?

Answer 1

Finding the fraction of salary is still left.​

Consider $Rs1$ as the total salary
Salary spent on food $=\frac{2}{5}\text{of}Rs1=Rs\frac{2}{5}$
So the remaining salary $=1-\frac{2}{5}$
It can be written as
$=\frac{5-2}{5}$
$=Rs\frac{3}{5}$

Now,
Salary spent on house rent $=\frac{3}{10}$ of $\frac{3}{5}$
$=\frac{3}{10}\times \frac{3}{5}=Rs\frac{9}{50}$

So the remaining salary $=\frac{3}{5}-\frac{9}{50}$
$[\text{LCM of}(5,50)=50]$
$=\frac{30-9}{50}=Rs\frac{21}{50}$

Hence, the fraction of salary left with the man is $\frac{21}{50}$.