OA is correct. We are looking for MAXIMUM possible...

$9a \times 5b= 1035$
Let us get 1035 in standard form .. 1035=1*5*9*23 or 1035=(-23)(-1)(5)(9) But a and b are positive..
Thus, possible values of a and b are 1 and 23 in any order.
we are looking for maximum value of a-b so take the maximum of two values as a, so a=23, and other as b, so b= 1..
23-1=22

Thank you 'bartendingliver' and 'chetan2u'.

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Posted from my mobile device

GIVEN: (9a)(5b) = 1035
Divide both sides by 9 to get: (a)(5b) = 115
Divide both sides by 5 to get: (a)(b) = 23

Since a and b are positive integers, there are only two possible solutions:
Solution #1: a = 1 and b = 23, in which case a - b = 1 - 23 = -22
Solution #2: a = 23 and b = 1, in which case a - b = 23 - 1 = 22

So, the MAXIMUM value of a - b is 22

Answer: 22

Cheers,
Brent

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