Question

In a cowshed there is enough food for 20 cows for 15 days. However, some cows were sold and the food lasted for 25 days. How many cows were sold?

Answer 1

Let $x$ cows were sold. Then,

$25(20-x)=20\times 15$

$500-25x=300$

$25x=200$

$x=8$

Therefore, $8$ cows were sold.