Custom fee fields with conditions

Hi OSTeam and Members:

We have a site that has several Membership options for classes. Example:
1. Select the number of Adults for the plan at $10 each, a custom fee field.
2. Add an Extra Class for the week, another custom fee field for the week to the Adult plan at  $8 each.

However, our problem is figuring out how to keep the Extra Class field to either not show or not work unless a person first selects the Adult plan choice.  Currently I can skip the first step and pay the discounted price for adding and Extra Class.

Thank you for your assistance.

Channing

Solved. Used Depend on to make work correctly.

Great. Happy to hear that and thanks for the update

Tuan