Question

If f(x)=7-3x and g(x)=3x-7, what is the value of f(1)-g(1)?

Answer 1

Substitute 1 for x in each of your equations.

f(x)=7-3x
which is
f(1)=7-3(1)
=3
Do the same for g(x)
g(x)=3x-7
which is
g(1)=3(1)-7
=-4

Then subtract g(x) from f(x):
3-(-4)
=7

:)