`a)`

`X:Al:x(mol);Cu:y(mol)`

`27x+64y=23,6(1)`

`4Al+3O_2` $\xrightarrow{t^o}$ `2Al_2O_3`

`2Cu+O_2` $\xrightarrow{t^o}$ `2CuO`

`n_{O_2}=3/4x+1/2y={9,916}/{24,79}=0,4(2)`

`(1)(2)->x=0,4;y=0,2`

`n_{Al_2O_3}=1/2x=0,2(mol);n_{CuO}=y=0,2(mol)`

`\%m_{Al}={0,4.27}/{23,6}.100\%=45,76\%`

`\%m_{Cu}=100-45,76=54,24\%`

`\%m_{Al_2O_3}={0,2.102}/{0,2.102+0,2.80}.100\%=56,04\%`

`\%m_{CuO}=100-56,04=43,96\%`

`b)`

`V_{kk}={9,916}/{20\%}=49,58(L)`