Pls meee with this question i have been stuck on it for forever

The rate of change is the slope.

That equation is (practically) in the form of y=mx+b because T(d) is very similar to y.

T(d) = 39.27d+36.77

   y =        mx+b

In this case, d would equal x. T(d) would equal y. 36.77 would equal b.

m is the slope, or the rate of change.

The rate of change is the variable, d, or the answer choice, a: the number of drinks purchased.