An automobile gasoline tank holds 22 kg of gasoline. when the gasoline burns, 86 kg of oxygen is consumed and carbon dioxide and water are produced. what is the total combined mass of carbon dioxide and water produced?

The law of conservation of mass states that mass is an isolated system and is neither created nor destroyed.

Applying this concept on a chemical reaction means that the total mass of reactants should be equal to the total mass of the products.

In this question, we have gasoline and oxygen as reactants and we have carbon dioxide and water as products.
Based on the law, the sum of the masses of oxygen and gasoline is equal to the sum of masses of carbon dioxide and water.
Therefore,
mass of carbon dioxide and water = 22 + 86 = 108 kg

And a) oxygen i believe