I have a simple problem here, some confusion on my part. I've just started learning about functions and their inverses. We've used traditional f^(-1) to denote the inverse. But recently, after learning real life applications, we learned another form. Say we have h(t) as a function of hour in terms of temperature. The inverse is now t(h) for temperature in terms of hours. My confusion is, h is the name of the function in h(t) but became the input for t(h) and vice versa for t. How can h serve both as the name of a function and a numerical variable at the same time?