When the price of a product was decreased by $10 \%$,the number sold increased by $30 \%$. What was the effect on the total revenue (in $\%$)?

On a test consisting of $150$ questions,Rita answered $40 \%$ of the first $75$ questions correctly. What per cent of the other $75$ questions does she need to answer correctly for her grade on the entire exam to be $60 \%$?

$A$ number,when $35$ is subtracted from it,reduces to its $80$ percent. What is four-fifths of that number?

Sweta invested $Rs. 10,000$ in a scheme exactly three years ago. The value of the investment increased by $10\%$ during the first year,increased by $5\%$ during the second year,and decreased by $10\%$ during the third year. What is the value of the investment today?

The price of an article was first increased by $10 \%$ and then again by $20 \%$. If the final increased price is $₹ 33$,what was the original price?

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