Problema Solution
suppose that the greatest common divisor of the positive integers X and Y is 21 and the least common multiple of X and Y is 252. The sum of all possible values of X is:
a) 20 b) 28 c)420 d)588
Answer provided by our tutors
We assume
X = 21m
Y = 21n
252 = 21*12 = 21*3*4 = 21*1*12
It can be
X = 21*3, 21*4, 21*12, 21
21*3 + 21*4 + 21*12 +21 = 420
So we choose c)420