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: How many odd 4-digit positive integers R that are multiples of 5 can be formed without using the digit 3?

 Option A: 648

 Option B: 729

 Option C: 900

 Option D: 1296

 Option E: 3240
[A]: Option A


[Q]: Question: A boat takes 19 hours for travelling downstream from point A to point B and coming back to a point C midway between A and B. If the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph, what is the distance between A and B ?

 Option A: 160 km

 Option B: 180 km

 Option C: 200 km

 Option D: 220 km

 Option E: None
[A]: Option B


[Q]: Question: If f(a)=2a+6, what is the value of (f(2a)+f(a)) ?

 Option A: 2a-4

 Option B: 8a-7

 Option C: 9a+5

 Option D: 6a+12

 Option E: 3a+5
[A]:
Option D