This equation is the same as
You can flip both sides to obtain
Does that give you any ideas?
Here is a quick way to get the answer on the SAT:
Simply raise both sides to the reciprocal power:
So grid in
(1) To solve this you only need to type the following into your calculator:
(2) If this were a multiple choice question you could simply plug the answer choices in for x in the original question. You should almost always start with choice (C) when using this strategy. (Of course the solution I have given is better, but it requires some mathematical knowledge, whereas this one does not.)
(3) Note that this problem is incomplete as you have stated it since -.25 is also a solution. So either you haven't written the question precisely or this isn't an actual SAT practice problem. In any case, the solution to a grid-in can't be negative.
(4) The above posters have given a better solution to this problem, but on the SAT you don't generally want the most complete solution. You want to get the answer as quickly and efficiently as possible.