Question

a farmer has enough grain to feed 60 cattle for 10 days for how many days will the grain last when there are 30 cattle

Answer 1

There is enough to feed the 30 cattle for 20 days because there is half the amount of cattle so you can do twice as many days.

Answer 2

Hi!

The simple explanation is just, since there are half as many cows, then the grain will last two times more.

But here's why. How many times are you going to be feeding the cattle, over 10 days, if you feed them once per day? 60 * 10 = 600, so 600 times.

If you're still feeding them once per day, and there are 30 cows instead, then find how many times 30 goes into 600. 600 / 30 = 20 days. That's a method you can use, no matter what, even if it's, say 50 cattle. You would still get an answer (if it was 50, 600 / 50 = 12, so 12 days).

Hope this helped!