Price for members 50%

Hello,
in the custom fields I would like the registrants to choose whether they are a member of the club or not.
Members have only to pay 50% of the price. Because I have now a percentage, I do not know how I should solve it with radio-buttons or checkboxes. There I could only enter values that were added.
Could "Fee formula" be the solution? For example with

[EB_BASE_PRICE] * 2 if not a member

or

[EB_BASE_PRICE] / 2 if a member

I think radio field with two options Yes/No would work. Use the following settings:

Fee Field:
Yes
Fee Values
0.5
1
Fee formula:
[INDIVIDUAL_PRICE]*[NAME_OF_THE_FIELD]

(NAME_OF_THE_FIELD must be replaced with name of this custom field in upper case)

After that, it will work

Regards,

Tuan

With a few small changes it works.

The fee values are now
-0.5
0

Ah, Yes. It needs to be -0.5 instead of 0.5

Tuan

Hi on this topic i am using a group billing form with the a child discount fee.
If a member has 4 people (2 adults, 2 children) booking at €50 each - i need to give a 50% child discount.
I have setup a list field called "childrate"
VALUES
Adults Only
1 Child
2 Children
3 Children
4 Children
5 Children
6 Children
7 Children
8 Children
9 Children
10 Children

FEE VALUES
0
-0.5
-1
-1.5
-2
-2.5
-3
-3.5
-4
-4.5
-5

FEE FORMULA
[INDIVIDUAL_PRICE]*[CHILDRATE]

This works fine however how can we prevent a users from entering e.g 3 registrants in the group billing then taking a discount for 4 children? In otherwords there should be a place for a conditional statement on the registrants number preventing this e.g something like
if (registrants_num > childrate){return "Error"} else {return "ok" }
Can this be done? Or is there a better method for giving a childrate with EB? would love to know!