Answer:
when you have something like f(x)=... that means
f means function
and every time you see an x or the variable in the parenthesis you plug in for that so it's f(x) =3x+1 then f(2)= 3x+1 every time you see x you plug in 2
137
you multiply 20 by 8 which you get 160 then you subtract 23 and then your answer is 137
