Aditya's salary was increased by $40 \%$ and then decreased by $25 \%$. Find the net effect on Aditya's salary.

If inflation increases at a rate of $8 \%$ p.a.,what will a $₹ 20$ article cost at the end of two years?

Suresh gave $40 \%$ of his income to his wife. He gave $25 \%$ of the remaining amount to his son. Of the remaining amount,he spent $60 \%$ on education. Now,the amount with him is $₹ 2700$. What is the amount he gave to his wife?

The population of a town $2$ years ago was $62500$. Due to migration to big cities,it decreases every year at the rate of $4\%$. The present population of the town is:

In a class of $80$ students and $5$ teachers,each student received sweets equal to $15 \%$ of the total number of students,and each teacher received sweets equal to $25 \%$ of the total number of students. How many sweets were there in total?

In a motor of $120$ machine parts,$5 \%$ parts were defective. In another motor of $80$ machine parts,$10 \%$ parts were defective. For the two motors considered together,the percentage of defective machine parts was (in $\%$)