Question

Your mother gave you $13.32 with which to buy a present. This covered 3/5 of the cost. How do you write and solve as an equation to find how much the present cost?

Answer 1

The present cost `$22.20`

Explanation:

Represent the cost of the present by the variable `color(blue)(c)`

We are told
`color(white)("XXX")color(red)(3/5 xx color(blue)(c) =$13.32)`
(this is the requested equation)

Multiplying both sides by `5/3` (to get rid of the fraction on the right side)
`color(white)("XXX")cancel(5)/cancel(3) xx cancel(3)/cancel(5) xx color(blue)(c)=(cancel($13.32)^($4.44) xx 5)/cancel(3)`

`color(white)("XXX")rarr color(blue)(c)= $22.20`

Answer 2

The cost of the present is `$22.20`.

Explanation:

The question can be restated as:

`3/5`th of the cost is `13.32`.

When "translating" words to an equation, "of" means multiplication and "is" means equal.

Let `x=` the cost.

`3/5 x = 13.32`

Multiply both sides by `5/3`

`5/3 * 3/5 x = 5/3 * 13.32`

`cancel5/cancel3 * cancel3/cancel5 x = (5*13.32)/3`

`x=22.2`, so the cost of the present is `$22.20`.