a rainstorm increased the amount of water stored in state j reservoirs from 160 billion gallons to 200 billion gallons . if the storm increased the amount of water in the reservoirs to 40 percent of total capacity , approximately how many billion gallons of water were the reservoirs short of total capacity prior to the storm ?
"let total capacity be x we know 200 = 0.40 x x = 200 / 0.40 = 500 prior to storm , we had 160 bn gallons 500 - 160 = 340 answer : d"
divide(divide(multiply(200, const_100), 40), const_2)