Can someone tell me how to do this plz

With math question will mark brainliest question in the pic.

Average salary for a medical assistant is $31,220 which is a 20% income tax bracket how much money would they pay in income tax?

Mr and mrs smith buy tickets for themselves and their four children. the cost of an adult ticket is ? 6 more than the adult ticket. the total cost of the six tickets is ? 40.50 work out the cost of an adult ticket. in your working let c be the cost of the child ticket and a be the cost of the adult ticket.