If a = b: + 4 and a - b = 7, what is a+b? give an exact answer, using fractions if necessary; no decimals.

Aswimming pool had 2.5 million liters of water in it. some water evaporated, and then the pool only had 22 million liters of water in it. what percent of the water evaporated?

How do i put 3(x+7) in distributive property

Tom drove 206 miles in 3.9 hours. estimate his average speed.