Math CentralQuandaries & Queries


Question from Susan:

If something costs 1.00/per lb. and that price includes a 25% discount. How do you calculate what the price was before the discount?

Hi Susan,

Let's do it the other way around. Suppose you knew the price was $2.00 per pound and you were to get a 25% discount, then you would only pay 75% of the $2.00 per pound. So the after sale price you get using the calculation

0.75 × $2.00 = sale price.

0.75 × $2.00 = $1.50 so the sale price is $1.50 per pound.

But you know the sale price, it's $1.00 per pound so whoever calculated this performed the calculation

0.75 × before sale price = $1.00.

If you now divide both sides by 0.75 you get

before sale price = $1.00/0.75 = $1.33.



About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS