The least bicycling hours we can have are 0, we cannot have less than 0 hours (because time can't be measured negative) and we can have as much as 13 bicycling hours, then the domain of the function must be the set of values between 0 and 13, including 0 and 13 and it can be written like this:
0 ≤ t ≤ 13
In order to specify the range of the function we just have to evaluate the time values that we used for the domain, like this:
At t = 0
M(0) = 12(0) = 0
At t = 13
M(13) = 12(13) = 156
Then, the range of the function should be:
0 ≤ M(t) ≤ 156