How much greater is a magnitude 4 earthquakes than a magnitude 3 earthquake?

Add 1/7 + -1/7 your answer should be reduced to its smallest form and should not be an improper fraction

If given an equation of a line such as -1/2x+6 how would you create an equation of a line parallel and perpendicula to this line that goes through another point such as (4,10)

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?