During a back-to-school sale, notebooks are on sale for 78% off the regular price. The cost of a notebook is represented by n. Which expression does NOT represent the sale
price of the notebooks?
A. 0.22n
B. (1 -0.78)n
C. n - 0.78n
D. 1 + 0.22n

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