No worries, we got this.

Alright, so let's take a look at C: "If a pair of curtains has been bought in the same ratio, how many red pairs of curtains would there be if there had been 64 pairs of yellow curtains?"

So we know that the ratios are 5:7:1:2. If there are 64 pairs of yellow curtains, how many times more 2 is that? 32. So if we are to apply that to our ratio, we get:

160:224:32:64

So how many pairs of red curtains are we looking at?