Which least number must be subtracted from each of the term 17, 31, 24, 45 to make them proportional?

3

To make these numbers in proportion, the condition should be:

(17 - a) : (31 - a) :: (24 - a) : (45 - a)

Check from the option, which is the best way to find the number.

So, Option (d):- 3 will justify the equation.

(17 - 3) : (31 - 3) :: (24 - 3) : (45 - 3)

    14    :      28    ::     21    :     42

     1     :       2    ::       1    :      2

Therefore, 3 is correct answer.