$5\mathrm{.}21.$ A stream of air mole $\%O_2,$ the rest $\{$:$N_2)$ flowing at a rate of $10\mathrm{.}0k\frac{g}{h}$ is mixed with a stream of $C{O}_2.$

The $C{O}_2$ enters the mixer at a rate of $20\mathrm{.}0\frac{m^3}{h}$ at $150C$ and $\frac{1\mathrm{.}5}{b}ar.$ What is the mole percent of $C{O}_2$

in the product stream?