Let's denote the skate rental cost as \( r \) and the cost per hour as \( c \).
From the problem, we can set up the following equations based on the information given:
For David: \[ r + 3c = 18.5 \]
For Jennifer: \[ r + 2c = 14.0 \]
Now, we can solve these two equations simultaneously.
First, let's subtract the second equation from the first:
\[ (r + 3c) - (r + 2c) = 18.5 - 14.0 \] This simplifies to: \[ c = 4.5 \]
Now that we have the cost per hour \( c = 4.5 \), we can substitute \( c \) back into one of the original equations to find the rental cost \( r \). Using Jennifer's equation:
\[ r + 2(4.5) = 14.0 \]
This simplifies to: \[ r + 9 = 14.0 \] \[ r = 14.0 - 9 = 5.0 \]
Thus, the answers are:
- The cost per hour is \( \boxed{4.5} \).
- The initial skate rental cost is \( \boxed{5.0} \).