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.

[Q]: Question: A can complete the job in 4 hours and B can complete the same job in 3 hours. A works for 1 hour and then B joins and both complete the job. What fraction of the job did B complete

 Option A: 1/7

 Option B: 3/10

 Option C: 1/2

 Option D: 5/6

 Option E: 8/9
[A]: Option A


[Q]: Question: A certain sum earns simple interest of Rs. 800 in 2 years at a certain rate of interest. If the same sum earns compound interest of Rs.900in the same period of 2 years, What must be the rate of interest?

 Option A: 25%

 Option B: 10%

 Option C: 15%

 Option D: 20%

 Option E: 30%
[A]: Option A


[Q]: Question: Find the value of y from (12)^3 x 6^4 ÷ 432 = y?

 Option A: 2234

 Option B: 4350

 Option C: 4560

 Option D: 5132

 Option E: 5184
[A]:
Option E