Problem: a rainstorm increased the amount of water stored in state j reservoirs from 130 billion gallons to 160 billion gallons . if the storm increased the amount of water in the reservoirs to 80 percent of total capacity , approximately how many billion gallons of water were the reservoirs short of total capacity prior to the storm ?
Rationale: "let total capacity be x we know 160 = 0.80 x x = 160 / 0.80 = 200 prior to storm , we had 130 bn gallons 200 - 130 = 70 answer : b"
annotated_formula: divide(divide(multiply(160, const_100), 80), const_2)