Question

John is buying candy and soda for a party. Candy costs

$4 per bag, and soda costs $3 per bottle. If John has a
combined total of 40 bags and bottles, and he spends
$130, how many bottles does he buy?

Answer 1

30 bags of Candy and 10 Sodas

Explanation:

We know that:

C + S = 40 [total of 40 bags and bottles]

The total price is expressed as:

$4C + $3S = $130 [The unit price times the number of items for both]

Dropping the $ for convenience (I'm lazy), we have two equations and two unknowns. A solution is possible.

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Rearrange one of the two equations to solve for one of the two variables. I'll use C + S = 40 and isolate C:

C = 40 - S

Now use this definition of C in the second equation:

4C + 3S = 130

4(40 - S) + 3S = 130

160 - 4S + 3S = 130

-S = -30

S = 30

From C + S = 40 we can find that S = 10

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CHECK

Do 30 bags of Candy and 10 Sodas add to $130??

30*($4) + 10*($3) = $130??

$120 + $30 = $130 ??? YES