`plural( N1, deskItem( 0 ) )` cost $`C`.

Which equation would help determine the cost of `plural( N2, deskItem( 0 ) )`?

`SOLUTION`

`\dfrac{`

`N2`}{\$`C`} = \dfrac{x}{`N1`}`\dfrac{`

`N2`}{`N1`} = \dfrac{\$`C`}{x}`\dfrac{`

`N1`}{`N2`} = \dfrac{x}{\$`C`}`\dfrac{x}{`

`N2`} = \dfrac{`N1`}{\$`C`}`\dfrac{`

`N2`}{x} = \dfrac{\$`C`}{`N1`}

There are several equations that could help determine the cost, each with a slightly different approach.

We can write the fact that `plural( N1, deskItem( 0 ) )` cost $`C` as a proportion:

`\dfrac{`

`N1`}{\$`C`}

Let `x`

represent the unknown cost of `plural( N2, deskItem( 0 ) )`. Since `plural( N2, deskItem( 0 ) )` cost `x`

, we have the following proportion:

`\dfrac{`

`N2`}{x}

The cost changes along with the number of `deskItem( 0 )`s purchased, and so the two proportions are equivalent.

Let `x`

represent the unknown cost of `plural( N2, deskItem( 0 ) )`. Since `plural( N2, deskItem( 0 ) )` cost `x`

, we have the following proportion:

`\dfrac{`

`N2`}{x}

We can write the fact that `plural( N1, deskItem( 0 ) )` cost $`C` as a proportion:

`\dfrac{`

`N1`}{\$`C`}

The cost changes along with the number of `deskItem( 0 )`s purchased, and so the two proportions are equivalent.

We know the cost of `plural( N1, deskItem( 0 ) )`, and we want to know the cost of `plural( N2, deskItem( 0 ) )`. We can write the numbers of `deskItem( 0 )`s as a proportion:

`\dfrac{`

`N1`}{`N2`}

We know `plural( N1, deskItem( 0 ) )` costs $`C`, and we can let `x`

represent the unknown cost of `plural( N2, deskItem( 0 ) )`. The proportion of these costs can be expressed as:

`\dfrac{\$`

`C`}{x}

The cost changes along with the number of `deskItem( 0 )`s purchased, and so the two proportions are equivalent.

If we let `x`

represent the cost of `plural( N2, deskItem( 0 ) )`, we have the following proportion:

`\dfrac{x}{`

`N2`}

We have to pay $`C` for `plural( N1, deskItem( 0 ) )`, and that can be written as a proportion:

`\dfrac{\$`

`C`}{`N1`}

Since the price per folder stays the same, these two proportions are equivalent.

`SOLUTIONS[ IDX ]`