John's sister went shopping with him. she expected to spend $100 on clothes, but spent only $10. john wanted to her calculate the percent error, but he thinks he may have made a mistake. are his calculations below correct? why or why not?
{$100-$10}/90 =10/90 = 11%

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?

10 ! a train starts from grand city and travels toward belleville 388 miles away. at the same time, a train starts from belleville and runs at the rate of 47 miles per hour toward grand city. they pass each other 4 hours later. find the rate of the train from grand city.

Find the area of the triangle shown 3 by 6