Hey everyone!

I'm here because I'm getting ready to write the GRE, and I'm stumped, since it's been 9 years since I did any math. (Though I was good at it back in the day!)

"The functionfis defined for all numbersxbyf(x) =x. If^{2}+ xtis a number such thatf (2t) = 30, which two of the following could be the numbert?

Indicatetwosuch numbers.

(Multiple choice: -5, -3, -1/2, 2, 5/2)"

Thanks in advance!