A rectangular-shaped carpet remnant that measures x feet by

x feet
y feet
total price = $50

find: cost of carpet ($/yd^2)

now the trap here would be for you to convert x feet and y feet using the given conversion in the question.

see, the conversion states that 9 square feet = 1 yard -->> if you analyze this statement it means square feet! SQUARE! this means that two units have already been multiplied (hope you're catching my drift)

this means that we should multiply x by y first, we have xy (area in square feet; this makes the conversion consistent)

(xy square feet) x (1 square yard)/(9 square feet) = xy square yard / 9 -->> see we want to cancel out square feet in numerator and square feet in denominator

now we want to get the cost of carpet per square yard, this means we just divide the total cost by what we got earlier; we have..

50/(xy/9) = 50 * 9 / xy = 450/xy

Answer is (E)

I think the main takeaway here is the trap that I said earlier. You have to think like the test maker. That being said, this question is very GMAT-esque, and I'm not surprised since the source is GMATPrep.

Anyway, can I get a kudos?

Thanks!