Dont Understand

[scenic needle]

If f(x) = 4x+x^2 and g(x) = x^4, then f(g(x)) = f(x^4) = 4x^4+x^8

[glad rivet]

they could have rephrased the question a better way

instead of saying f(x), g(x) they could have said f(g(x))

[gray abyss]

They clearly mentioned f o g

The comma separation is so the automated system understands the input

But composition is often confusing since the student is unsure whether to perform f first or g first