Pls Explain

[Nycgrl]

. If a, b, and c are integers, is the number divisible by 3?
(1) a + b is divisible by 3.
(2) c is divisible by 3.

OA- B.....Pls Explain

[parallel_chase]

If a, b, and c are integers, is the number divisible by 3?

which number are we talking about is it a+b+c or abc or a,b & c are three digits of the number?

[Nycgrl]

. If a, b, and c are integers, is the number 3(a+b)-c divisible by 3?
(1) a + b is divisible by 3.
(2) c is divisible by 3.

[parallel_chase]

. If a, b, and c are integers, is the number 3(a+b)-c divisible by 3?
(1) a + b is divisible by 3.
(2) c is divisible by 3.

The answer is B

From the question stem itself we know that a+b will be multiple of 3, therefore we just have to find the value of C.

Statement I

a + b is divisible by 3

we dont know anything about C. Insufficient.

Statement II

C is a multiple of 3, therefore 3(a+b)-c will always be a multiple of 3 hence divisible by 3.

Sufficient.

Here is rule that you can learn.

If a and b are divisible by n then a-b & a+b both will be divisible by n