Solve the Problem $20 \%$ Of the Actual Cost of Their Dinner, with the Club

Solve the problem.
-A banquet dinner is being organized by a club. The members are to pay $20 \%$ of the actual cost of their dinner, with the club making up the difference. Club members are told that they are to pay $\$ 4$ to attend. What is the actual cost of the dinner?

A) $\$ 21$
B) $\$ 18$
C) $\$ 22$
D) $\$ 20$