Quandaries and Queries


I'm having trouble figuring out how to figure a percentage??? it's easy to find what 40% of any given number is, but how would i accurately figure out what is the final number is when i know the number after the 40% has been removed? when i add 40% to this number it obviously is lower than it should
be. the best i could figure is;
x=?-40% ---------------> x-?=-40% i'm all confused????

any help would be greatly appreciated.

Thanks much



Hi Cathy,

Think of what you do in the "forward" direction. If you have $250 and you want to remove 40% of it you have

$250 - 40% of $250
= $250 - 0.4 $250
=$250 (0.6) = $150

Now suppose that you buy something at a shop for $150 and you know that the original price of this item was reduced by 40% to arrive at the $150. If the original price was $x then, looking at the equation above, the shopkeeper calculated

$x 0.6 = $150

To find x, divide both sides by 0.6 to get

($x 0.6)/0.6 = $150/0.6 or
$x = $250

A similar argument works if you want to add 40%. Suppose you bought an item for $420 and you know that the shopkeeper's markup is 40%. Then the shopkeeper took her price, $x, and multiplied by 1.4 to get the $300 price. That is

$x 1.4 = $420


$x = $420/1.4 = $300

So the shopkeeper paid $300 for the item.



Go to Math Central