If the 8-digit number 98x423y4 is divisible by 72, then what is the value of (5x + 3y -xy), for the maximum value of y?
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Correct answer: C
Explanation
The correct answer is option 3 i.e. 3.
98x423y4 must be divisible by 72 (Divisible by both 8 and 9)
Divisibility by 8: The Last 3 digits 3y4 is divisible by 8
If y = 8, then 3y4 = 384 [Divisible by 8]
Sum of digits = 38 + x
If x = 7, then 38 + x = 45 [Divisible by 9]
(5x + 3y - xy) = 5(7) + 3(8) - (7 × 8) = 35 + 24 - 56 = 3