To solve this you must simply add $2.10 + $4.45 together to get a sum of $6.55. Next, you must subtract the $6.55 from $13.50 to get a difference/final solution of $6.95. So, in conclusion, Luke made a profit of $6.95 from mowing the lawn.
Subtracting 3.25 hours from 10 PM is subtracting 3 hours and 15 minutes from 10 PM. Doing this, we get that the game started at 6:45 P.M. Hope this helped!