E F asked:

Here is the case : Minor designs a product and an adult promises to give the minor 50% of profits from that product. The minor does not need to do anything anymore and only the adult needs to do something – pay the minor a percentage.

The problems I’ve seen relating to contracts with minors is that the minor can void the contract and not be bounded by it , but here in this case the minor has nothing to void since the adult just promised to pay 50% of profits and the minor didn’t promise to do anything.