Give the step-by-step reasoning process and then the final answer. Selina is selling some of her old clothes to a second-hand store. They will buy her pants for $5 each, her shorts for $3 each, and her shirts for $4 each. She sells 3 pairs of pants, 5 pairs of shorts, and some shirts. After she gets her money, she sees 2 shirts that she likes which cost $10 each and buys them. She leaves the store with $30. How many shirts did she sell to the store?
The shirts she bought cost her $20 because 2 x 10 = 20. She earned $50 selling her clothes because 20 + 30 = 50. She made $15 off pants because 3 x 5 = 15. She made 15 dollars from shorts because 3 x 5 = 15. She made $20 off shirts because 50 - 15 - 15 = 20. She sold 5 shirts because 20 / 4 = 5.
The final answer: 5.