question:One copy machine can make 20 copies a minute, and a second copy machine makes 10 copies a minute. If the two copiers work together, how long would it take them to make 900 copies?
Options:
(A) 10 minutes
(B) 20 minutes
(C) 25 minutes
(D) 30 minutes
(E) 35 minutes
answer:(D)
Stream of consciousness:Total work done by both machines in a minute = 20 + 10 = 30 copies
Total number of copies required = 900
Time = 900/30 = 30 mins


question:A 70 cm long wire is to be cut into two pieces so that one piece will be 2/5th of the other, how many centimeters will the shorter piece be?
Options:
(A) 10
(B) 20
(C) 30
(D) 40
(E) 50
answer:(B)
Stream of consciousness:1: 2/5 = 5: 2
2/7 * 70 = 20


question:The edge of a cube is 6a cm. Find its surface?
Options:
(A) 216a2
(B) 24a4
(C) 24a1
(D) 24a2
(E) 24a7
answer:

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
(A)
Stream of consciousness:6a2 = 6 * 6a * 6a = 216a2