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:

$A$ and $B$ together have ₹ $1210$. If $\frac{4}{15}$ of $A$'s amount is equal to $\frac{2}{5}$ of $B$'s amount,how much amount (in ₹) does $B$ have?

Two numbers are in the ratio $1: 2$. If $7$ is added to both,the ratio changes to $3: 5$. The greatest number is:

What must be added to each term of the ratio $2:5$ so that it may equal to $5:6$?

If $x: y = 2: 1,$ then $(x^{2} - y^{2}) : (x^{2} + y^{2})$ is

₹ $600$ is divided among $A, B$ and $C$. If $\frac{2}{5}$ of $A$'s share plus ₹ $40$,$\frac{2}{7}$ of $B$'s share plus ₹ $20$,and $\frac{9}{17}$ of $C$'s share plus ₹ $10$ are all equal,then what is $A$'s share in ₹?