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!
Answer:
the hallway
Step-by-step explanation:
it's a reasonable length
the answer is a, please mark me brainliest!
Step-by-step explanation:

Divide the top and bottom by the highest number that can divide into BOTH numbers.