Answer:
6 days
Explanation:
Each hamster eat
of a cup of grain a day.
So in one day, the three hamsters eat:
cups
And since we know that Mary has 6
cups of grain.
We need to convert this quantity into a fraction:

she has
cups of grain.
To find how many days the grain will last, we need to divide the total amount of grain she has (
cups) by the amount that the three hamsters eat together in one day (
cups):
÷

and we use the rule to divide fractions:
÷

this way we get:
÷

the grain will last 6 days