Question

On a recent trip to the convenience store, you picked up 2 gallons of milk, 6 bottles of water, and 7 snack-size bags of chips. Your total bill (before tax) was $25.65. If a bottle of water costs twice as much as a bag of chips, and a gallon of milk costs $1.90 more than a bottle of water, how much does each item cost?

Answer 1

The water costs $1.90, the chips are $.95 and the milk is $3.80.

Explanation:

Let m = milk

Let w = water

Let c = chips

2m+6w+7c =25.65 w = 2c m = w + 1.90

For the first equation, substitute w for 2C and m for w + 1.90 to get:

2(w+1.90) +6(2c) + 7c = 25.65

2w+3.8+12c+7c=25.65

2w+19c = 21.85

Now substitute 2c for w:

2(2c)+19c =21.85

4c + 19c = 21.85

23c = 21.85

c = .95 Now that we know the cost of the chips we can use that to find the water and the milk for the original equations that we wrote at the top.

w = 2c

w=2(.95) = 1.90

m = w + 1.90 = 1.90+1.90 = 3.80