A = 2x3xm, B = 3x5xm. A, the greatest common factor of B is 21, M = ()

A = 2x3xm, B = 3x5xm. A, the greatest common factor of B is 21, M = ()

A = 2x3xm, B = 3x5xm. A, the greatest common factor of B is 21, M = (7)