Two elements x and y have atomic masses of 14 and 16 respectively. They form a series of compounds A, B, C, D and E in which for the same amount of element; x, y is present in the 1: 2 : 3 : 4 : 5. If the compound A has 28 parts by mass of x and 16 parts by mass of y, then the compound of C will have 28 parts by mass of x and: