I invested R100,000 in a business which is in operation.

Answer

The R100,000 you had invested was in lieu of stock, equipment, etc. in the business. You became 40% owner of the assets of the business, and this entitles you to 40% of the profit. The R100,000 no longer belongs to you. It became the property of the person from whom you had purchased the 40% share in the business. Hence, there is no Zakaat payable by you on the R100,000.