At the grocery store grapes cost $2.55 for 2 pounds. At the farmers market grapes cost $3.55 for 3 pounds. What is the unit rate for each store? Which is ther better deal?

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