Company is sold for $2 billion.
Investor invested $100mn
Due to 2x liq.pref, investor will first get $200mn ($100mn x 2)
Remaining amount left is $1.8 billion
Then investor will get 15% of $1.8bn which is $270mn
So total amount investor gets $270mn + $200mn = $470mn

The money an investor make while selling the company depends on the method of valuation and the agreement enter into between the investors and the organisation