Answer:
$5
Explanation:
We are given that profit equation
![P(x)=-2x^2+20x+0](https://img.qammunity.org/2022/formulas/mathematics/high-school/g7wrh7lhv9t4od8pd9fiftmkxp2snq0j9o.png)
Where x=Charges per pair of mittens
We have to find the charge per pair of mittens to make her max profit.
Differentiate equation w.r.t x
![(dP)/(dx)=-4x+20](https://img.qammunity.org/2022/formulas/mathematics/high-school/4b4i7i1gkzmat4de0ip7oicfl8uk7i0a1t.png)
![(dP)/(dx)=0](https://img.qammunity.org/2022/formulas/mathematics/high-school/73jukqpx26nw4eccn15m6nt7qqdy143ymp.png)
![-4x+20=0](https://img.qammunity.org/2022/formulas/mathematics/high-school/ocxz48pgfoscq9qpbnd4vagxo42tfz1tu3.png)
![4x=20](https://img.qammunity.org/2022/formulas/mathematics/high-school/5am8olovu4z1d5vmkrv7ksp22worz9kjxz.png)
![x=5](https://img.qammunity.org/2022/formulas/mathematics/high-school/vndazmbyqu3wu39zuuyki1lbj4enalp9m1.png)
Again differentiate w.r.t x
![(d^2P)/(dx^2)=-4<0](https://img.qammunity.org/2022/formulas/mathematics/high-school/ywe7bv4abr10mii78vgnlepshm353q9zgo.png)
Hence, the profit is maximum at x=5
Lily should charge $5 per pair of mittens to make her max profit .