Answer:
Step-by-step explanation:
sales - expenses = profit
lets x represent number of shirts sold
12x - (3x + 150) > = 300
12x - 3x - 150 > = 300
9x - 150 > = 300
9x > = 300 + 150
9x > = 450
x > = 450/9
x > = 50 <== they would need to sell at least 50 shirts