Ratio and percentage related

Question

The ration of boys to girls in a school is 7:6. If the number of boys and girls in the school increases by 10% and 15% respectively in one year, the number of boys will exceed the number of girls by 120. What is the total number of students in the school?

Answer 1

Hint: Suppose total number of girls after increment is $x$ and total number of boys after increment is $y$ then,

$$x+120=y$$

Answer 2

Let us note $b$ the current number of boys and $g$ the current number of girls. What we know is that today $$\frac bg=\frac 76$$ that is to say $$6b=7g$$ Within a year, there will be $1.10 b$ boys and $1.15 g$ girls and you are told that the situation will be such that $$1.10b-1.15g=120$$ So, two equations for two unknowns $b$ and $g$.

I am sure that you can take from here.