Answer:
40%
Explanation:
The profit margin is given by the gross profit divided by total sales.
In this case, Gadget mania has a gross profit of $6 per microphone, while each microphone sells for $15.
Therefore, the profit margin is:
![P=(6)/(15)\\P=0.4=(40)/(100)= 40\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/6rjajaxlqukgqjbwypiyn7ck63ugdq40ng.png)
Gadget Mania's profit margin is 40%.