200 feet = 200 * 0.3048 = 60.96 m
e = 0.5 * g * t ^2
e = 60.96
g = 9.8 m/s2
t = ?
t^2= 60.96 / 0.5 * 9.81 = 12.440
t = 3.5271 s
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
:)