Answer:
0.8 kilograms of fertilizer
Explanation:
Looking at the data given to us in a fraction form, we can imagine:
4 kilograms / 5 weeks
To find out how many kilograms of fertilizer was used each week, we're going to divide that fraction out, so we're going to do 4 divided by 5. Dividing this will give you:
0.8 kilograms
Therefore your answer is that they use .8 kilograms of fertilizer each week.