Question

Nitric acid is produced commercially by the Ostwald process, represented by the following equations.
4 NH3(g) + 5 O2(g) 4 NO(g) + 6 H2O(g)
2 NO(g) + O2(g) 2 NO2(g)
3 NO2(g) + H2O(l) 2 HNO3(aq) + NO(g)
What mass in kg of NH3 must be used to produce 4.4 multiplied by 106 kg HNO3 by the Ostwald process, assuming 100% yield in each reaction?

where do i even begin?!