Q: What is the difference between 80% of 170 and 35% of 300.
Options:
(A) 30
(B) 29
(C) 37
(D) 36
(E) 31
A: OK... Stream of consciousness: (80/100) * 170 â€“ (35/100) * 300
136 - 105 = 31
The answer is (E).

Q: Find the simple interest on Rs.500 for 9 months at 6 paisa per month?
Options:
(A) 277
(B) 270
(C) 288
(D) 266
(E) 121
A: OK... Stream of consciousness: I = (500*9*6)/100 = 270
The answer is (B).

Q: In a is a positive integer smaller than 200 and (14a)/60 is an integer, then a has how many different positive prime factors?
Options:
(A) 2
(B) 3
(C) 5
(D) 6
(E) 8
A: OK... Stream of consciousness: 7a/30 tells us that a is a factor of 30, which has 2, 3, and 5 as its prime factors. Each of them is distinct. Moreover, all multiples of 30 less than 200 can be derived by multiplying these prime factors alone. Thus, number of different prime factors is 3.
The answer is (B).

Q: Ann invested a certain sum of money in a bank that paid simple interest. The amount grew to $240 at the end of 2 years. She waited for another 3 years and got a final amount of $300. What was the principal amount that she invested at the beginning?
Options:
(A) $150
(B) $175
(C) $200
(D) $210
(E) $220
A:

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
OK... Stream of consciousness: Amount at end of 2 years = 240$
Amount at end of 5 years = 300$
Difference in amount for time period of 3 years = 60$
Annual Interest earned = 60/3 = 20$
Principal amount invested at the beginning = 240 - 2*20 = 200$
The answer is (C).