The ratio of wine and water in a drum is $3:1$. What part of the mixture is taken out and replaced with an equal amount of water so that the ratio of wine and water in the mixture becomes $1:1$?

Hitesh is $40$ years old and Ronnie is $60$ years old. How many years ago was the ratio of their ages $3:5$?

Two candles of the same height are lighted at the same time. The first is consumed in $8 \text{ hours}$ and the second in $6 \text{ hours}$. Assuming that each candle burns at a constant rate,in how many hours after being lighted,the ratio between the height of the first and second candles becomes $2:1$?

Present ages of $X$ and $Y$ are in the ratio $5: 6$ respectively. Seven years hence,this ratio will become $6: 7$ respectively. What is $X$'s present age in years?

Three numbers $A, B$ and $C$ are in the ratio $12: 15: 25$. If the sum of these numbers is $364$,find the ratio between the difference of $B$ and $A$ and the difference of $C$ and $B$.

The ratio of students in school $A, B$ and $C$ is $5: 4: 7$ respectively. If the number of students in schools are increased by $20\%$,$25\%$ and $20\%$ respectively,then what will be the new ratio of students in school $A, B$ and $C$?