For this case we have an equation of the form:
 
 Where,
 A: initial amount
 b: growth rate
 x: number of years
 Substituting values we have: 

 By the time the earnings increase to 75000 we have: 

 From here, we clear x: 
 
 Answer:
 you will have to wait until 23.95 years your winnings are worth $ 75,000