The water company has a different monthly on water used in hundreds of cubic feet HCF as shown below Cost in dollars t 214 104 Residential Plan Business Plan Monthly water usage in HCF a If the monthly water usage is 18 HCF which plan costs less Residential Plan Business Plan How much less does it cost than the other plan b For what amount of monthly water usage do the plans cost the same monthly water usage is more than this amount which plan costs more S