Hello

First of all, thank you very much because you put the brackets just like you had to do !

Now, the problem ^^

You can notice that in the solution, there is no more 25 or 50, etc... So we'll simplify by factoring as much as possible

But so :

Simplify by 5 :

Now, you can notice that the red term is very similar to what you want to get : .

Actually, .

This gives you the trick : multiply the denominator & the numerator by

--->

But .

Is it clear enough ?