On Tuesday last week, Leo dropped off 10 pairs of trousers and some shirts at Sudsy Laundry. He was given a bill of $140, charged at $5 per shirt and $9 for each pair of trousers. When he went to pick up his clothes yesterday, the attendant insisted that he had only dropped off 2 shirts. Leo reported the matter to the manager, who ordered the attendant to search for the rest of Leo’s shirts. How many shirts were missing?
Solve it.