q: The edge of a cube is 5a cm. Find its surface?
Options:
(A) 24a8
(B) 150a2
(C) 24a1
(D) 24a2
(E) 24a7
a: OK... 6a2 = 6 * 5a * 5a = 150a2
The answer is (B).

q: A train 120 m long running at 60 kmph crosses a platform in 35 sec. What is the length of the platform?
Options:
(A) 338
(B) 277
(C) 463
(D) 456
(E) 271
a: OK... D = 60 * 5/18 = 35 = 583 – 120 = 463
The answer is (C).

q: From the set of numbers x, y, t, z, s and w, how many different combinations can we have without the t in them? Ex:. (x,y), (x), (w,z,y,x,s), etc and (x,y)=(y,x)
Options:
(A) 10
(B) 14
(C) 15
(D) 16
(E) 31
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... Another way: Any letter (x, y, z, w, s) can be included or not. So, we have 2^5 combinations - 1 empty combination = 31 combinations
The answer is (E).