rohan2345 wrote:
If x and y are positive integers, is x divisible by 3?
(1) x-y is divisible by 3.
(2) x-2y is divisible by 3.
Given: x and y are positive integers.
Asked: Is x divisible by 3?
(1) x-y is divisible by 3.
x-y = 3k where k is an integer=> x-y =3,6,9.... If y =1 x=4,7,... but if y=3, x=3,6,9...
NOT SUFFICIENT
(2) x-2y is divisible by 3.
x-2y=3k where k is an integer => x-2y =3,6,9.... If y=1 x=5,8,... but if y=3, x=3,6,9...
NOT SUFFICIENT
Combining (1) & (2)
(1) x-y is divisible by 3.
(2) x-2y is divisible by 3.
Subtracting (2) from (1)
(x-y)-(x-2y) = y is divisible by 3
From (1) x is divisible by 3.
SUFFICIENT
IMO C
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