Question

Question #103d5

Answer 1

I got `50`

Explanation:

Consider the total as `x` (corresponding to `100%`); we can write that:
`x/9` must be the same as `(100%)/(18%)`
or:
`x/9=(100%)/(18%)`
rearranging:
`x=9*(100cancel(%))/(18cancel(%))=50`

Answer 2

`50`

Explanation:

"Percent" literally means "per `100`". If we say something is `18%`, that is the same as writing `18/100`. When we say `18%` of a number, it is similar to how we might say `3` of a number. In the latter case, we would multiply by `3` to represent it algebraically. In this case, we multiply by `18% = 18/100`.

Let `x` represent our number. Writing our given information algebraically, then, we get

`18/100x = 9`

`=> 18/100x * 100/18 = 9*100/18`

(we multiply by the reciprocal of the coefficient of `x` to make `1` the new coefficient of `x`)

`:. x = 50`

Answer 3

`18% xx 50 = 9`

Explanation:

You can work this out by writing an equation using `x` as the unknown number.

`18% " of what number is equal to " 9`?

`18/100 xx x = 9" "larr` now solve the equation for `x`

`x = 9 xx100/18`

`x = cancel9 xx100/cancel18^2`

`x = 50`