Question

find (fog)(x) if f(x)=x-x^2 and g(x)=3x+2

Answer 1

first get rid of that circle and write
\[f\circ g(x)=f(g(x))\] then work from the inside out
replace \(g(x)\) by \(3x+2\) and write
\[f(g(x))=f(3x+2)\]

Answer 2

then, wherever you see an \(x\) in \(f(x)\) replace it by \(3x+2\) to get
\[f(3x+2)=3x+2-(3x+2)^2\]