Question 1024111
Call the number of phones he bought, x.
Profit = Receipts - Costs
Plugging into that we get
850 = 1120(x-5) - 950x
Now solve this and we get
850 = 1120x - 5600 - 950x
6450 = 170x
x = 6450/170 = 37.94  or almost 38 phones