Let N = 553 + 173 - 723. N is divisible by
- both 3 and 17
- both 7 and 13
- both 3 and 13
- both 17 and 7
Answer
55 + 17 = 72
Use formula
(x - y)3 = x3 - y3 - 3xy(x-y)
(72 - 17)3 = 723 - 173 - 3(72)(17)(72 - 17)
553 + 173 - 723 = 3(72)(17)(55)
N is divisible by both 3 and 17.
The correct option is A.