7.3  Proportion
We will learn to determine an unknown value using the unitary method.
  • Proportion is a comparison between two different quantities of units and is usually expressed as one quantity per unit of another quantity.
  • Rates can be found by dividing the two quantities involved.
  • The unit of rate measurement is the unit of numerator per unit of the denominator.


A car can travel 350 km with 50 litres of petrol. How far would it be if the car was only filled with 20 litres of petrol?


50 litres = 350 km
20 litres = ___ km

\(\frac{350 \text{ km}}{50\text{ liter}}=\frac{?}{20\text{ liter}}\)


20 litres = 140 km