If the number of bacteria in a colony doubles every 45 minutes and there is currently a population of 500 bacteria what will the population be 180 minutes from now? (WILL GIVE THANKS)

Problem number 26 of the rhind papyrus says: find a quantity such that when it is added to of itself the result is a 15. the modern day equation that models this problem is x + x = 15. what is the solution to the equation? x = 10 x = 12 x = 15 x = 30