Answer :

Given that a farmer can feed 20 animals in his cattle for 6 days and also let the food will now last for x days.

Clearly we see that, more is the number of animals, less will be the number of days for food to last.So, it is a case of inverse proportion.

∴\( 24 \times 6 = 30 \times x \)

\(\Rightarrow x= \frac { 20\times 6 }{ 30 } = 4\)

Hence, the food will now last for 4 days.