An automobile gasoline tank holds 21 kg of gasoline. When the gasoline burns, 82 kg of oxygen is consumed and carbon dioxide and water are produced.What is the total combined mass of carbon dioxide and water that is produced?

Your balanced equation. ( standard for this type problem )

2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O

------We work in grams because that is what is on my periodic table.

21 kg gasoline = 21,000 grams

82 kg oxygen = 82,000 grams

------get moles of reactants

21,000 grams gasoline (1 mole/114.224 g) = 183.85 moles gasoline

82,000 g oxygen (1 mole O2/32 g) = 2562.5 moles O2

------find limiting reactant.

183.85 moles gasoline (25 moles O2/2 moles C8H18) = 2298.125 moles in ratio.

------Gasoline limits as you have nowhere near that amount of gasoline moles. Drive reaction with gasoline moles.

183.85 moles gasoline (16 moles CO2/2 moles C8H18)(44.01 g/1 mole CO2)

= 64,729.91 g = 64.73 kg of carbon dioxide.

======

183.85 moles gasoline (18 moles H2O/2 moles C8H18)(18.018 g/1 mole H2O)

= 29,813.48 g = 29.81 kg of water

======

95 kilograms total combined mass

======