Which of the following is an EXPRESSION? 12 + 3 = 15
5a + 21 = 41
7(d - 1) + 2
2x - 16y = 56

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