Task B-1.4. A cattleman has secured food for his 24 cows for 18 weeks. How many cows would he have to sell after 8 weeks so that he would have enough food for another 12 weeks?
## First solution.

Let $x$ be the number of cows the farmer needs to sell.

The total amount of food is $24 \cdot 18$ weekly required amounts and it does not change, but is only reallocated to the amount needed for 24 cows for 8 weeks and $24-x$ cows for 12 weeks.

Then we have

$$
24 \cdot 18 = 24 \cdot 8 + (24 - x) \cdot 12
$$

From this, we get $x = 4$. The farmer needs to sell 4 cows after 8 weeks.