Given that f(x)=x 2+3x+6 and g(x) =x-3, solve for f(g(x))when x=1

F(x)=x²+3x+6   and g(x)=x-3, to calculate f(g(x)), let's replace x in f(x) by
(x-3) in g(x):
f(g(x)) = (x-3)² + 3(x-3) + 6
f(g(x)) = x²-6x+9 + 3x-9 +6
f(g(x)) = x²-3x+6, :
f(g(1)) = 1² -3(1) + 6:
f(g(1)) = 4

If you make it a little more clear i can answer it