Calculations are as follows:
Price of the barbecue= $10
Customers served in a day= 50
Sales = 50 * $10= $500
Expenses or total cost per customer = $7
So with 50 customers, the cost is $7 * 50 = $350
Net Profit = Sales - Expenses/Costs
$500 - $350 = $150 Net Profit Per Day with 50 customers daily