If f(x)=√x + 12 and g(x)=2√x what is the value of (f-g)(144)?

F(x) = \sqrt(x)
g(x) = 2\sqrt(x)

(f-g)(x) = \sqrt(x) - 2\sqrt(x)
(f-g)(144) = \sqrt(144) - 2\sqrt(144)
(f-g)(144) = 12 - 24
(f-g)(144) = -12

F(144)= sqrt(144)+12                         g(144)= 2(sqrt(144))

f(144)= 12+12                                    g(144)= 2(12)
f(144)=24                                           g(144)=24
                              (24)-(24)=0