a museum gives a discount to school groups on Mondays.it charges a group rate that includes a fee of $6.00( which includes the teacher).they also charge $0.50 for each child or additional adult. the cost for ms.kapales's third grade class to go to the museum last monday with two parents accompanying them was $19.50.how many children are in her class?

a) 25 b) 26 c)20 d)27