<h2>
Answer:</h2>
Yes, the relationship between the amount charge and the number of hours is proportional.
The unit rate is: $ 15 per hour.
<h2>
Step-by-step explanation:</h2>
Two variables x and y are said to be in direct proportion if:
or
Here x represents the number of hours of baby sitting
and y represents the charges.
Since, the ratio is constant.
Hence, the amount charge and the number of hours is proportional.
Also, the unit rate is: $ 15 per hour.