###Human: Ronald wants to make profits by re-selling some phones he bought a week ago. He bought 200 units for just $3000, and he wants to gain a third of the initial investment in profits when all units are sold. Including the profit margin, what will be the selling price for each phone?, ### Assistant: The profit Ronald wants is $3000 / 3 = $1000
The profit per phone sold will be $1000 / 200 phones = $5/phone
The cost of each phone is $3000 / 200 phones = $15/phone
The selling price including the profit will be $15/phone + $5/phone = $20 
 So the answer is :  20