# The price of a box of 15 cloud markers is $12.70. The price of a box of 42 cloud markers is $31.60. All prices are without tax, and the price of the boxes is the same. How much would 50 cloud markers in a box cost?

##### 2 Answers

The cost of 1 box of 50 markers is

#### Explanation:

This is a simultaneous equation type problem.

Let the cost of 1 marker be

Let the cost of 1 box br

15 markers + 1 box = $12.70

42 markers + 1 box =$31.60

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Eliminate

Use the count of

Substitute the cost of 1

Use all this information to determine the cost of a box of 50

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divide both sides by 27

Using

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The cost of 1 box of 50 markers is

The total cost of

#### Explanation:

Check whether we are working with a direct proportion, in which case the comparison between the price and the number of markers would be the same.

The prices differ, so they are not directly proportional.

The reason is that both prices include the price of the box, which is the same. This can be thought of as the constant.

If you were to draw a graph of price (on the

Let's find the slope.

Therefore each marker costs

the price of

How much does the box cost?

Consider

The box itself costs

The total cost of

Another way to find this answer would be to draw the graph accurately and read off the value where

graph{y= 0.7x+2.2 [-4.03, 75.97, -1.72, 38.28]}