A company has developed an online application for smart mobile phones, the users who installed the app. in 2015 were 6000 users, and they increase by 15% each succeeding year. If the company gains on average annual revenue of OMR 15 per user. a) What is the total revenue gained until the end of the year 2022? b) After how many years from the beginning, the annual revenue of the company will reach about OMR 240000?

i want answer in this method , Finding the sum of the first n terms of a GP (Sn):

= ( 1) 1 ; > 1