Find the difference in weight of figs before and after they are dried. One kg of dried figs costs $11.25$ while one kg of fresh figs costs $9$. A farmer has 20 kg of fresh figs. What is the difference in weight of the farmer's figs before and after they are dried?

$x$ kg of dried fig + $y$ kg of water = $1$ kg of fresh fig

$11,25x = 9,0$ -> It means that we are interested in the solid part. Water does not care.

$x = \frac{9,0}{11,25} = 0,8$

So, our initial formula is

$0,8$ kg of dried fig + $0,2$ kg of water = $1$ kg of fresh fig