Dependent variable h depends upon two independent variaables, one of which is represented by 50 and the other by the letter t. In other words, h is a function of two variables. Without further detail it is impossible to describe the behavior of this function h=f(50,t).
Suppose that h = f(x,t) = 2x - 1/t. This is my invention.
Then f(50,t) would come out as 2(50) - 1/t, which is a function of just 1 variable.