An oxide of copper ($C{u}_{x}O$ ) was reduced in a stream of hydrogen into metallic copper as shown below.
$H_2+C{u}_{x}O\to Cu+H_{2}O$  Unbalanced

After heating, the stream of hydrogen gas was maintained until the apparatus had cooled to avoid reoxidation of copper. Neither water nor adsorbed hydrogen traces are found in the dish. The following results were obtained.
Mass of empty dish = 13.80 g.
Mass of dish and contents before heating = 21.75 g.
What is the Mass of dish along with contents after heating and leaving to cool (in grams)?
Atomic mass of copper and oxygen are 63.55u and 16.00u respectively. Equivalent mass of $C{u}_{x}O$ in the reaction is 39.775