A student sells fancy shirts on campus for $100 each while purchasing them for $20 each. She starts the day with $100 in cash. In the morning, she buys 5 shirts. By the end of the day, she has sold 3 units for cash. She also spent $20 in food (assume this as an operating expense). What is her profit for that day? a. $300 Ob. $280 Oc. $220 d. $180 e. $100