The population of fresno california was 762,565 in 1980. the population in 1990 was 836,231. find the percent of increase

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