Dave bowers collects u. s gold coins. He has a collection of 47 coins. Some are $10 coins, and the rest are $20 coins. If the face value of the coins is $670, how many of each denomination does he have?

Suppose that in 2008 , 840,800 citizens died of a certain disease assuming the population of teh country is 399 miliion, what is the mortality rate in units of deaths per 100,000 people?

An internet company charges $8.95 per month for the first 3 months that it hosts your web site. then the company charges $11.95 per month for web hosting. how much money, in dollars, will the company charge for 8 months of web hosting?

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.