Anu spends 90% of her income. If her expenditure increases by 25% and savings increase by 30%, then by what percent does her salary increase?

Let initially Anu was getting $$=X Rs.$$

So, initial expenditure $$=\dfrac{90\times X}{100}=\dfrac{9X}{10}$$

and initial savings $$=\dfrac{10X}{100}=\dfrac{X}{10}$$

As per the condition, expenditure increased by $$25\%$$. So $$=\dfrac{9X}{10}+\dfrac{9X\times 25}{10\times100}=\dfrac{45X}{40}=\dfrac{9X}{8}$$
Saving increase by $$30\%$$. So $$\dfrac{X}{10}+\dfrac{X\times 30}{10\times 100}=\dfrac{13X}{100}$$
Hence, New salary= total expenditure + total saving $$=\dfrac{9X}{8}+\dfrac{13X}{100}=\dfrac{251X}{200}$$

Hence, percentage of increase Anu's salary$$=\dfrac{(\dfrac{251X}{200}-X)\times 100}{X}$$
$$=\dfrac{(251X-200X) \times 100}{200 \times X}$$
$$=\dfrac{51X}{2X}$$
$$=25.5\%$$