Answer:
$75 + $17.50t
 $56 + $19.50t
Explanation:
Let us assume the number of hours be t
Now according to the equation 
For Joe 
= $75 + $17.50t
And, for Maddie 
= $56 + $19.50t
The expression that represents the total is as 
$75 + $17.50t
 $56 + $19.50t
Hence, the above represent the answer and the same is relevant