Two glasses together contain 280 mlof water. the first glass contains 80 ml more than the second glass. how much water does the first glass contain?

Can someone me out here and the tell me the greatest common factor

At the electronics store you have a coupon for 20% off up to 2 cds you buy for cds with the original cost of $10.99 each the sales tax is 5% what is the total cost of your purchase

Akayaker travels 3 miles upstream and 3 miles downstream in a total of 4 hours. in still water, the kayaker travels at a speed of 2 mph. what is the average speed of the river's current?