GMAT Problem Solving (PS) | Re: A grocery store bought some mangoes at a rate of 5

Please explain whats the issue with my approach. Break even means no profit no loss.

3 mangoes bought at 5$ per mango = 15$ cost price.
1 mango sold at 3$ per mango = 3 $
2 Mangoes sold at 6$ per mango = 12 $

Ratio should be 1:2