The ratio of the number of boys and girls in a school of $720$ students is $7: 5$. How many more girls should be admitted to make the ratio $1: 1$?

Two alloys contain zinc and copper in the ratio of $2:1$ and $4:1$. In what ratio should the two alloys be mixed to get a new alloy having zinc and copper in the ratio of $3:1$?

An employer reduces the number of his employees in the ratio $9:7$ and increases their wages in the ratio $14:15$. Find the ratio in which the total bill of wages increases or decreases.

Find the compound ratio of $2:7$,$5:3$,and $4:7$.

₹ $1050$ are divided among $A, B$ and $C$ in such a way that the share of $A$ is $\frac{2}{5}$ of the combined share of $B$ and $C$. $A$ will get (in ₹):

If $a-b : b-c : c-d = 1 : 2 : 3$,then what is the value of $(a+d) : c$?