Question

John and 3 friends are going out for pizza for lunch. They split one pizza and 4 large drinks. The pizza cost $13.00. After using a $6.00 gift certificate, they spend a total of $13.20. Write an equation to model this situation, and find the cost of one large drink.

Answer 1

The total amount they spent is the cost of pizza and 4 large drinks. This amount is also the sum of the amount of gift certificate and the cash $13.20. Let x be the price of each drink. The equation would be,
                           13 + 4x = 6 + 13.20
The value of x from the equation is 1.55. Thus, each large drink costs $1.55. 

Answer 2

13 + 4x - 6 = 13.20
x = (13.20 -13 + 6) / 4x = 1.55
one large drink costs $1.55