\(V_{hh}=V_{C_2H_2}+V_{H_2}=3V_{H_2}+V_{H_2}=4V_{H_2}=20\left(m^3\right)\)
\(\Rightarrow V_{H_2}=5\left(m^3\right),V_{C_2H_2}=15\left(m^3\right)\)
\(C_2H_2+\dfrac{5}{2}O_2\underrightarrow{t^0}2CO_2+H_2O\)
\(H_2+\dfrac{1}{2}O_2\underrightarrow{t^0}H_2O\)
\(V_{O_2}=\dfrac{5}{2}V_{C_2H_2}+\dfrac{1}{2}V_{H_2}=\dfrac{5}{2}\cdot15+\dfrac{1}{2}\cdot5=40\left(m^3\right)\)