At a store, 24 bottles of water and 6 bags of chips costs $23.40. Five bottles of water and two bags of chips cost $6.60. What is the cost of a single bottle of water?

24w+6c=$23.40

5w+2c=$6.60

So you have to find c (chips) first. You have to make the number of chips in both equations cancel each other.

-3(5w+2c)=-3($6.60)

-15w-6c=$-19.80

Then subtract to get one formula

24w + 6c = $23.40

-15w - 6c = $-19.80

9w = $3.60

w=$.40

To check your answer, find how much one bag of chips costs:

5($.40) + 2c = $6.60

$2.00 + 2c = $6.60

2c = $4.60

c=$2.30

Plug your value for one water and one bag of chips into the formula:

5($.40) + 2($2.30)

$2.00 + $4.60

=$6.60

Then plug your values into the original problem:

24($.40) + 6($2.30)

$9.60 + $13.80

=$23.40

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