Very confused on this question, whats the answer and why

You just put the fractions where they say they are supposed to be, so put 7/4 in for y and put 7/6 in for x. Then, you have to first do the exponent since it comes first in PEMDAS, so after that you solve the exponent, you get -343/-216. Next, you have to do 7/4- 343/-216. After that you get the fraction 35/216.

She should use 12/3 to measure