What is the mean of the numbers given below? 2,2,8,10,15,30,36,40,50,51
report your answer in decimal form

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