Final answer:
Musa has 3/5 ton of grain and uses 1/20th of it each day, so it will take 12 days to use all the grain.
Step-by-step explanation:
The question asks how many days it will take for Musa to use all his grain if he uses 1/20th of it each day to feed the animals on his farm. To solve this, we need to determine how many 1/20th portions makeup 3/5th of a ton. Since both fractions have a common denominator of 20 when you multiply 3/5 (12/20) by 20, you get an answer of 12 days. Therefore, it will take Musa 12 days to use all 3/5 tons of grain at the rate of 1/20th per day.