F(x)=x-3; g(x)=5x^2 me solve this function in algebra.

Your question is incomplete. the actual question probably ask you to solve these functions for a value of X.
for example the following function for X=2 will be:
f (2) = 2-3= -1.
g (2)= 5×(2^2) = 20

so please go back to the question and find out what is being asked

I’d say letter a..