### 1.2.1.2 Algebra

Algebra overcomes this ambiguity.
Once we have defined x,y, z then their meaning is fixed precisely for ever. We can define x as the number of grams of pollutant per litre. To do this we would take a litre of the liquid, boil of the water and weigh what was left. This gives us a precise measure of pollution. We can then define that over such and such grams per litre, water is very polluted etc. etc.

The point is we can avoid ambiguity. Thus at least everyone is meaning the same thing when they communicate. We will find later that this is one of the biggest difficulties in problem solving - adopting the same perceptions.