Dimethylamine burns in oxygen according to the following equation:

4 C2H7N + 15 O2 → 8 CO2 + 14 H2O + 2 N2
(a) How many liters of O2 at 35 °C and 0.840 atm will be needed to burn 7.70 L of C2H7N at 35 °C
and 0.840 atm?
(b) How many liters of CO2 at 35 °C and 0.840 atm will be produced?
Report your answers to parts (a) and (b) to 3 significant figures

I have anwsered this elsewhere.