F(x) =x^2+6x and g(x)=7-x find (f-g)(x) and (f-g)(9)

F(x)=x²+6x
g(x)=7-x

(f-g)(x) means that f(x)-g(x), so
f(x)-g(x)
=x²+6x-7+x
Combining like terms
x²+6x+x-7
=x²+7x-7, so (f-g)(x)=x²+7x-7
Next,
(f-g)(x)
=x²+7x-7
(f-g)(9)
=(9)²+7(9)-7
=81+63-7
=144-7
=137, so (f-g)(9)=137. Hope it help!