Some more possibilities

Define and compose:
f(x) := x^2[br][br]g(x) := 1/(x - 1)[br][br]fog := f(g(x))
Invert
h(x) := 2x + 5[br][br]Solve[h(x) = y, x][br][br][br][br][br][br][br][br][br][br]
Define and function and invert it. (Try different functions)
h(x) := 2x + 5[br][br]Invert[$1]
– Mathías Tejera

Information: Some more possibilities