If $18 \%$ of a number is $720,$ then what is $81 \%$ of the same number?

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 $\%$)?

The number that is to be added to $10 \%$ of $320$ to have the sum as $30 \%$ of $230$ is

Six-elevenths of a number is equal to $22 \%$ of a second number. The second number is equal to one-fourth of a third number. The value of the third number is $2400$. What is $45 \%$ of the first number?

When a number is divided by $12$,the quotient becomes $1/4$ of another number. By what percentage is the first number greater than the second number?

The population of a town increases by $12 \%$ during the first year and decreases by $10 \%$ during the second year. If the present population is $50400$,what was it $2$ years ago?