Molar gas volume

A student burns 20.0 cm³ of butane gas completely in 120.0 cm³ of oxygen. The equation is $C_4H_{10}(g) + 6.5O_2(g) \rightarrow 4CO_2(g) + 5H_2O(l)$. Assuming all volumes are measured at the same conditions, what is the total volume of gas present after the reaction?