Would GRE test makers ever do this?

Would the GRE ever write an algebraic expression question where two separate variables using two different letters would be used to represent the same number?

In this question, because variables are being used, I assumed each variable with a different letter always represents unique numbers (a=/=b=/=c=/=d). But the question solution says to consider the case where c=d in order to find the right answer. Pictures below.


There is nothing to suggest that they have to be different.

So I shouldn’t make that assumption for GRE questions either?

Indeed, no.

Got it thank you!