Cambridge Review TestPrep CD question

[wagoboy]

If x^5 = 4, and x^4 = 5/y, what is y?

Sorry I can't recall the 5 choices, but would be great if someone can show how to break down this question

[torontogmat.com]

depends on whether the answer choices are numeric, or in terms of x.

you can ballpark a number in your head, but I'm assuming the answer choices will be in terms of x.

x = 4^(1/5) from statement 1.

therefore, x^4 = 4^(4/5) = 5/y, so y = 5 / 4^(4/5), which I'm guessing is just under 2.

[its_me07]

x^4.x=4
5x/y.x=4 as x^4=5/y
so
y=5x/4