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: Two pipes A&B can fill a tank in 24 min and 32 min respectively. If both the pipes are opened simultaneously, after how much time B should be closed so that the tank is full in 18 min.

 Option A: 8 min

 Option B: 3 min

 Option C: 21 min

 Option D: 23 min

 Option E: 24 min
Option A

Question: What is the place value of 3 in the numeral 3259

 Option A: 2700

 Option B: 2800

 Option C: 2900

 Option D: 2980

 Option E: 3000
Option E

Question: The average age of three persons is 52 years. Their ages are in the proportion of 1:5:7. What is the age in years of the oldest one among them.

 Option A: 9 years

 Option B: 12 years

 Option C: 60 years

 Option D: 70 years

 Option E: 80 years

Option D