Reasonably, the domain is all nonnegative rational numbers, like 3 23/60 hours or 3 hours 23 minutes. Nonnegative because you cannot babysit for a negative time period. We could further limit the domain, to x <= 168 if we determined that babysitting is limited to periods of less that one week. Then, x is rational and
0 <= x <= 168.
Reasonably, the range is limited to rational numbers, since your payment for babysitting is limited to dollars and cents, cents being hundredths of dollars. Based on the arbitrary limit of one week of babysitting. Then M(h) is rational and 0 <= M(h) <= 840, the dollar amount earned for 168 hours at $5.00 per hour, the pay rate defined by the function.
The mathematical domain of this function is all real numbers.
The mathematical range is all real numbers.
M(8) represents the amount of money earned for 8 hours of babysitting. The function M returns $40 for 8 hours babysitting.