SOLUTION: At the football game, 3 hamburgers and 6 soft drinks cost $21, and 3 hamburgers and 3 soft drinks cost $15. Which two equations can be used to determine the price of a hamburger an

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: At the football game, 3 hamburgers and 6 soft drinks cost $21, and 3 hamburgers and 3 soft drinks cost $15. Which two equations can be used to determine the price of a hamburger an      Log On


   

Question 1127777: At the football game, 3 hamburgers and 6 soft drinks cost $21, and 3 hamburgers and 3 soft drinks cost $15. Which two equations can be used to determine the price of a hamburger and the price of a soft drink?
Let x represent the cost of a hamburger and y represent the cost of a soft drink.
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!
(1)   3x + 6y = 21  
(2)   3x + 3y = 15

This system can be quickly solved for y by, say, subtracting eq(2) from eq(1):


                3y = 6

                 y = 2  —>  3x = 21-12 = 9 —> x = 3 




Cost of items:

Hamburg:  $3

Soft drink:  $2

——




Check:



3*3 + 6*2 = 9+12 = 21 ✔

3*3 + 3*2 = 9+6 = 15 ✔