I see that its a kuta software page. Search up the name of the topic at the top left and then at the end put kuta software. It works like a charm.
The store owner sold 4/5 of the suitces. That means 1/5 of the suitcases are left. Multiple 225 to 1/5
There are 45 suitcases left
(2,4) and (5,13) is m=-1/3 and (4,5) and (9,-3) is m=-8/5