Well we want to find out how much more will it cost to rent a ski boat than a sailboat for four hours.
All we have to do is Multiply 73 by 4 for the sailboat which gives you $292
Now we do the same for the ski boat. $88 * 4 = $352
So we now have to find out how much more it will cost for a ski boat than a sail boat. All we do is subtract 352 by 292
352
-
292
====
$60
Your answer is $60