If the price of a book is first decreased by $25 \%$ and then increased by $20 \%,$ then the net change in the price will be

In an examination in which full marks were $800,$ $A$ gets $20 \%$ more than $B,$ $B$ gets $20 \%$ more than $C,$ and $C$ gets $15 \%$ less than $D.$ If $A$ got $576,$ what percentage of full marks did $D$ get (approximately) (in $\%$)?

In a mixture of milk and water,the proportion of water by weight was $75 \%$. If $15 \text{ gm}$ of water is added to $60 \text{ gm}$ of this mixture,what will be the new percentage of water by weight (in $\%$)?

If $25 \%$ of a number is subtracted from a second number,the second number reduces to its $5/6$. What is the ratio of the first number to the second number?

The population of a variety of tiny bushes in an experimental field increased by $10 \%$ in the first year,increased by $8 \%$ in the second year,but decreased by $10 \%$ in the third year. If the present number of bushes in the experimental field is $26730$,then the number of bushes in the beginning was:

If $8 \%$ of $x = 4 \%$ of $y,$ then $20 \%$ of $x$ is: