how much flour is needed to add for making porridge

Question

 

To prepare old granma’s porridge you need 3.5 liters of water for every kilogram of flour. If you
pour 2.8 liters of water in a pot, how much flour do you have to add?

 

Answer 1

Let's put this into some equations.  The recipie calls for

3.5l of water / 1kg of flour

that means we can take a percentage 2.8 as a percentage of 3.5 and multiply the percentage by 1kg to get the amount of flower

2.8/3.5=.80

.80 times 1kg

.8kg or 800g