Answer
f(g(x))=g(f(x)=x
Work Step by Step
Show that f(g(x))=g(f(x)=x.
f(g(x))=f(4x+9)=(4x+9-9)/4=4x/4=x
g(f(x))=g($\frac{x-9}{4}$)=4($\frac{x-9}{4}$)+9=x-9+9=x
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