Question 950665
At Happy Burger you can get one order of fries and one burger for $7.20. You can also get three orders of fries and seven burgers for $38.60. What is the cost of each item?
1x + 1y = 7.20
[-1x -1x]
y = -1x + 7.20 
:
3x + 7y = 38.60
Replace y with (-x+7.20)
3x + 7(-x+7.20) = 38.60
distribute
3x - 7x + 50.4 = 38.60
3x - 7x = 38.60 - 50.40
-4x = -11.80
x = -11.80/-4
x = $2.95 is the price of the fries
Find the price of the burger
7.20 - 2.95 = $4.25 for the burger
:
:
Check this out using your 2nd equation
3(2.95) + 7(4.25) = 
8.85 + 29.75 = 38.60