Answer:
[tex]36\ liters\ of\ soil[/tex]
Step-by-step explanation:
we know that
The ratio of soil, manure and leaf mould is [tex]3:1:2[/tex]
That means
For every 6 liters of the compost, he use 3 liters of soil
so by proportion
Find how many liters of soil does he use for 72 liters of compost
[tex]\frac{3}{6}=\frac{x}{72}\\ \\x=3*72/6\\ \\x=36\ liters\ of\ soil[/tex]