Arnie bought some bagels at 20 cents each. He ate 4, and sold the rest at 30 cents each. His profit

[math_celebrity]

Arnie bought some bagels at 20 cents each. He ate 4, and sold the rest at 30 cents each. His profit was $2.40. How many bagels did he buy?

Let x be the number of bagels Arnie sold. We have the following equation:
0.30(x - 4) - 0.20(4) = 2.40

Distribute and simplify:
0.30x - 1.20 - 0.8 = 2.40

Combine like terms:
0.30x - 2 = 2.40

Add 2 to each side:
0.30x = 4.40

Divide each side by 0.3
x = 14.67 ~ 15