Question

The price of a calculator is decreased by

31
%
and now is
$
189.06
.
Find the original price.

Answer 1

Original price is $274

Explanation:

Let

x = Original price of calculator ($)

Percentage decrease =
`(Original Price - New Price)/(Original Price)`×
`100`%

31% =
`[(x - 189.06)/(x)]` ×
`100`%

`(31)/(100)` =
`(x - 189.06)/(x)`

0.31 =
`(x - 189.06)/(x)`

Cross-multiplication is applied:

`(0.31)(x)` =
`(1)(x - 189.06)`

Distributive Law is applied to expand the brackets or parentheses:

`0.31x` =
`x - 189.06`

Like terms are brought together. At the same time, the unknown variable

x is isolated and made subject of the equation:

`189.06` =
`x - 0.31x`

`189.06` =
`0.69x`

`x` =
`(189.06)/(0.69)`

∴ x = Original price of the calculator = $274