The answer is 14 because 14 x 4 = 56 so 1 of every 4, 14 times
They are inverse functions though to be completely thorough your teacher should have also put g(f(x)) = x as well. Though I can see what your teacher is aiming for at least.
The idea is that whatever the output of g(x) is, it's plugged into f(x) and the initial input is the result. So g(x) takes a step forward and f(x) takes a step back undoing everything g(x) did. Which is exactly what an inverse operation does.
They are either the same, or opposite number.
The length of the edge would be 5cm
