Math help?? Percents and Discounts ?

"The 299.99 cell phone Brittany purchased was on sale for 10% off. What amount did Brittany get off the price ?

Please explain the procedure because there are tons of questions like that so I really need to know how to solve it so I can figure out the rest

Anonymous2014-08-27T14:29:41Z

you take 299.99 x .10=29.99 299.99-29.99=270.00 Brittany got 29.99 off the phone. If it would of been 5% then you would take 299.99 x .05=14.95 understand?

Battleaxe2014-08-27T14:26:55Z

10% = 0.10
0.10(299.99) = 29.999, rounds to 30.00
She got 30.00 off the original price.