The number that must be added to each of the numbers $8, 21, 13$ and $31$ to make the ratio of the first two numbers equal to the ratio of the last two numbers is:

If ₹ $126.50$ is divided among $A, B$ and $C$ in the ratio of $2: 5: 4$,the share of $B$ exceeds that of $A$ by (in ₹) (in $.50$)?

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 $2:1$?

Annual incomes of Amit and Varun are in the ratio $3:2,$ while the ratio of their expenditures is $5:3.$ If at the end of the year each saves $Rs. 1000,$ the annual income of Amit is (in $Rs.$):

Gold is $19$ times as heavy as water and copper is $9$ times as heavy as water. In what ratio should these be mixed to get an alloy $15$ times as heavy as water?

At present,Kavita is twice Sarita's age. $8 \ yr$ hence,the respective ratio between Kavita's and Sarita's ages will be $22:13$. What is Kavita's present age (in $yr$)?