If the 8-digit number 789x531y is divisible by 72, then the value of (5x – 3y) is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. -1.
If a number is divisible by 72 it must be divisible by 8 and 9
789x531y is divisible by 72.
The last 3 digits 31y must be divisible by 8:
⇒ Then the possible value of y is 2
For divisibility by 9:
⇒ 7 + 8 + 9 + x + 5 + 3 + 1 + 2 must be divisible by 9
⇒ 35 + x must be divisible by 9
⇒ Possible value of x is 1
(5x – 3y) = 5 - 6 = -1