santro789 wrote:

Can we back solve this question anyway?

Hey

santro789Sure u can! But it is just too time consuming.

When back solving always remember to start from the middle option so that you know wether u should test higher values or lower values.

Luckily in this question 2.5 is the middle value and we can arrive at the AC quick.

So since it is a fraction it wont matter if u take A/B as 2/5 or 200/500. Just make sure B/A is equal to 2.5 because we are testing for it.

You will see that by adding the A and B with 6 and 15 will always give us \(\frac{2}{5}\).

Example - \(\frac{2}{5}\) is \(\frac{2+6}{5 +15}\) = \(\frac{8}{20}\) = \(\frac{2}{5}\).

Hence C is the option.

Hope it helps!