GMAT Data Sufficiency (DS) | Re: If x and y are positive integers such that x = 8y + 12, what

x = 8y + 12 simplifies to x=4(2y+3)

Statement 1:
substituting x=12u

12u=4(2y+3)
3u=2y-3
3(u-1)=2y

So u should be greater than 1 and should be odd (because u-1 is a multiple of 2)
Checking for values

u x y GCD
3 36 3 3
5 60 6 6

So statement 1 not sufficient

Statement 2:
substituting y=12z

x=4(12z+3)
x=12(4z+1)

Checking for values

z x y GCD
1 60 12 12
2 108 24 12
3 154 36 12
we can check for more values but usually we would see any variations
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