Problem
Fuel 1,000 kg/h, actual air 18,000 kg/h, theoretical air 14 kg/kg fuel.
Formula
A/F=ma/mf; excess air=(actual−theoretical)/theoretical×100
Solution
A/F=18; excess=(18−14)/14×100.
Answer
18 kg/kg and 28.57% excess air
Engineering check
Verify units, magnitude, assumptions and physical meaning before accepting the result.