Sally has £520 Katie has £360
Sally and Katie are each going to give 15% of their money to charity.
Work out the total amount of money they give to charity.

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