Khabab start his own business few years after his graduation from AUIS, He invested $$40,000$ of his saving and his family's money in the business. $8$ years later he fallin love with a girl and decided to get married.Unfortunately, the girl said I will only marry you if you sell the business, that way you will have more time for me$,$ Khabab was crazily in love he accepted the offer. Few months later he sold the business for $$600,000.$ They got married and they lived happily ever after. What rate of return did Khabab got from his company $?$