For a+b to be divisible by 15, it must be divisible by the prime factors of 15, ie, 3 and 5.AAPL wrote:If a and b are integers, is a+b divisible by 15?
(1) a+b is divisible by 30.
(2) a+b is divisible by 5.
The OA is A.
I need help to solve this DS question. Please, can any expert explain it for me? Thanks.
(1) a+b is divisible by 30.
Since the prime factors of 30 are 2, 3 and 5, a+b is divisible by 15. Sufficient.
(2) a+b is divisible by 5.
For a+b to be divisible by 15, it must be divisible by 3 too. From the statement, we are not sure whether it is also divisible by 3. Insufficient.
The correct answer: A
Hope this helps!
-Jay
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