As a part of 'Refer & earn' program, you need to make a minimum investment of 20$ in order to become eligible for referral benefits. Moreover, your friend must have clicked on the link shared by you.
You will earn 20$ when your friend joins Mudrex with your referral and invest a minimum of 20$ in any of the Coin Set.
NOTE- Investing the same reward amount of 10$ multiple times won't really help! Once your friend invest altogether of 20$, you will be rewarded with a 20$ rewarded as promised!
For any other query, please raise a ticket!