A rectangular waterbed is 7ft long 6 ft wide and 1 ft tall how many gallons of water are needed to fill the waterbed assume 1 gallon is 0.13 cu ft round to the nearest whole gallon

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