Johnny ran a race in 15 seconds, Malik ran the race in 4,92 seconds less then Johnny, How long did it take Malik to run the race?

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