Math Destroyer Functions

[matty675]

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Hey guys,
I'm going through Math Destroyer and am having trouble with some of the functions. I understand the basics of function composition, but this one seems to be a bit of a curve ball:

If G(F(x))=x^2-3 and G(x)=x-3, find F(3).

It seemed really basic at first and so I plugged 3 into the first equation to get 6, but the answer is 9. I can't understand how they arrived at the answer because the solution is so vague. Dr. Romano says, "Since G(F(x))=x^2-3 and G(x)=x-3, then F(x) must be x^2 by the composition of functions. F(3) is therefore 3^2=9."

Any help would be appreciated.

 

[FeralisExtremum]

The question does not ask you to find G(F(3)), which is what you calculated, but F(3). You are told what G(F(x)) is, and what G(x) is, so you can deduce that F(x) = x^2