Given
Cost = C = 15.82
Profit = P = 6.18
Sold 1 glass 0.50
Number of glasses sold = x
Equation
P = x*0.5 - C
Solve
6.18 = x*0.5 - 15.82 Add 15.82 to both sides
6.18 + 15.82 = 0.5x
22 = 0.5x Divide by 0.5
22/0.5 = x
x = 44
He sold 44 glasses of Lemonade to make 6.18 profit.
