If rupee one produces rupees nine over a period of 40 years, find the rate of simple interest?
Options:
(A) 22 1/8 %
(B) 22 9/2 %
(C) 22 1/7 %
(D) 22 1/2 %
(E) 21 1/2 % Hmmm, my stream of consciousness:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
9 = (1*40*R)/100
R = 22 1/2 % So, the answer is (D).