principle of atomic conservation(POAC)?

Question

use da principle of atomic conservation 2 solve da question below.
1g of a mixture of cuprous oxide and cupric oxide was quantitatively reduced to 0.839 g of metallic copper. what was the weight of cupric oxide in the original sample.

Answer 1

63.563 + 16 = 79.563
127.126 + 16 = 143.126
x*79.563 + y*143.126 = 1
x*63.563 + y*127.126 = 0.839
x = 0.006925497
x*79.563 = 0.551 g cupric oxide