this will get you started ...
now do the same to solve for y in terms of n ... then evaluate
my apologies ... I assumed you had some knowledge regarding the Laws of Exponents
Basically,
If its SATs, AS A RULE, forget about complex rules.
...(1)
and
... (2)
From (1),
Cross multiply and shift the x-term to the left hand side, you get:
... (3)
Multiply (2) and (3)
Squaring on both sides and making a reciprocal of the left-hand and the right-hand-side term gives:
<= Answer