Tom and his friend edward are seeking to join a gym. tom saw on television that platinum gym was having a grand opening in a few months. tom is considering a membership at platinum gym. platinum gym charges a one-time registration fee of $60, and membership is $20 a month. tom's best friend edward says he plans to join super fit because super fit only charges $10 a month but has a one-time registration fee of $150.
write an expression to represent the membership cost of platinum gym for x months