a certain protective additive increases from 30 days to 60 days the time between required maintenance checks on an industrial vehicle . by what percent is the time between maintenance checks increased by using the additive ?
"general formula for percent increase or decrease , ( percent change ) : percent = change / original ∗ 100 so , the time between maintenance checks increased by ( 60 − 30 ) / 30 ∗ 100 = 100 answer : c"
multiply(divide(subtract(60, 30), 30), const_100)