Which expression represents, twice the difference of two numbers?

(a) 2(x−y)

(b) 2−x−y

(c) 2x−y

(d) 2(x+y)

According to statistics a person will devote 32 years to sleeping and watching tv. the number of years sleeping will exceed the number of years watching tv by 18. over a lifetime, how many years will the person spend on each of these activities

How many glue sticks are in a basket containing 96 scissors, if the ratio of glue sticks to scissors is 19 to 57.

The sum of the speeds of two trains is 720.2 mph. if the speed of the first train is 7.8 mph faster than the second train, find the speeds of each.