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Bunuel
If a and b are positive integers, what is the greatest common factor of a and b?

(1) The greatest common factor of half of a and half of b is 7.
(2) a is 14 and b is an even multiple of 21



Statement 1: The greatest common factor of half of a and half of b is 7.

HCF of a/2, b/2 = 7
=> HCF of a, b = 14.

So Sufficient.


Statement 2: a is 14 and b is an even multiple of 21.
a = 14.
b = 2* 21, or 4*21, or 8* 21 and so on.
In any case b will always contain 14.

So HCF(a,b) = 14.

So Sufficient.


Answer D.
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a,b > 0; GCF(a,b) = ?

Statement 1: GCF( a/2 , b/2 ) = 7
a/2 = 7*x*y*
b/2 = 7*u*v

GCF( a,b) =14
Sufficient

Statement 2: a = 14 ; b = even multiple of 21
b = 3*7*2*k
GCF (a,b) = 14
Sufficient

Answer : D
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If a and b are positive integers, what is the greatest common factor of a and b?

a , b > 0 .. GCD (a,b) ?

(1) The greatest common factor of half of a and half of b is 7.
GCD (0.5a , 0.5b) = 7
so a , b has to be multiple of 7 ... Sufficient

(2) a is 14 and b is an even multiple of 21

a= 14 =7*2
b= 21*2*k = 7* I
so GCD of a , b is 7 .. Sufficient

ANs is D
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Kindly see the attachment
D. Both are sufficient.
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1.PNG [ 24.46 KiB | Viewed 3045 times ]

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