At the beach, denise and her sister both built sandcastles and then measured their heights. Denise's sandcastle was 1 7/12 feet tall and her sister's was 5/12 of a foot tall. How much taller was denise's sandcastle than her sister's? In mixed number

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