instruction:
You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
question:
Question: Working alone at its constant rate, machine K took 3 hours to produce 1/5 of the units produced last Friday. Then machine M started working and the two machines, working simultaneously at their respective constant rates, took 6 hours to produce the rest of the units produced last Friday. How many hours would it have taken machine M, working alone at its constant rate, to produce all of the units produced last Friday?

 Option A: 10

 Option B: 12

 Option C: 15

 Option D: 25

 Option E: 30
answer:
Option C


question:
Question: Two trains of equal are running on parallel lines in the same direction at 45 km/hr and 36 km/hr. The faster train passes the slower train in 36 sec. The length of each train is?

 Option A: 45

 Option B: 88

 Option C: 66

 Option D: 55

 Option E: 22
answer:
Option A


question:
Question: In an election only two candidates contested. A candidate secured 70% of the valid votes and won by a majority of 180 votes. Find the total number of valid votes?

 Option A: 450

 Option B: 570

 Option C: 480

 Option D: 520

 Option E: 550
answer:

Option A