1.1 Introduction
If the apple costs 3 crowns and two apples cost 6 crows, then three apples should cost 9 crowns. This is an example of a proportional relation, in other words the cost increase equally for every apple.

Foto: Fredrik Enander 
Imagine that you are going to bake some buns for 60 people instead of 20. You need to use the proportion of ingredients in order for the buns to taste like the recipe for 20 buns.
If you increase or decrease the number of portions in a recipe, this is an example of proportionality.
Cinnamon Buns
Ingredients for 20
1/2 packet yeast(á 50 g)
50 g butter or margarine
3 dl milk
0.5 dl sugar
1 pinch salt
8 dl flour 
Foto: Fredrik Enander 
Kalle works in a kiosk and earns 70 kr/hour. After two hours, he has earned 140 kr and after three hours he has earns 210 kr.
We say that Kalle’s salary is proportional to the number of hours that he works. 
Foto: Fredrik Enander 
