If a bank charges $1.50 for each atm transaction linked to a checking account, which of these equations can be used to solve for the number of monthly atm transactions x that is equivalent to a $19.50 monthly service fee? a.) $1.50+x=$19.50 b.) $1.50x=$19.50 c.) $19.50x=$1.50 d.) $19.50+x=$1.50