So I find it helps to start by writing some definitions down, as such let
y=teaspoons of sugar and
x=candy bars
I named to two variables in this problem as such largely because the problem itself gave names for them.
Now we can take the original question and put in 'y' and 'x' in place of 'teaspoons of sugar' and 'candy bars' respectively.
"A recipe requires 2.5 y to make 1 x"
Note that I supplied the 1 for the candy bars, or x. The original wording of the question did not have the number 1, but it did have the word 'a', which implies the same thing.
Now all we need to do is rewrite the equation once more to not have any words in it, this can be done largely by just getting rid of 'A recipe requires', and turning the words 'to make' into an equals sign.
As such,
2.5 y = x
Note that I got rid of the 1 in front of x because x on its own can be understood to mean 1.
Looking at the possible answers then, none say 2.5 y = x, but the fourth one says x = 2.5 y, which is our answer backwards. Therefore the fourth answer would be the correct one.
I hope that helps!
