Bunuel wrote:
x, y, a, and b are four positive integers. D is the greatest common divisor of x and y. Is D > 20?
(1) x = 10a + 20b
(2) y = 20a + 40b
We are clearly given that x, y, a, and b are four
positive integer
Stat 1: lets sub a = 1 and b = 1 , we get x as 10+20 = 30...Not sure about y...Insufficient. ( we can't take a or b as 0, because 0 is neither positive or negative)
Stat 2: y = 60..not sure about x value..Insufficient.
Both : 30 and 60 are the numbers and GCD is 30...Sufficient.
IMO option C.