Answer:
They can take in cats for 9 more days before they reach capacity.
Explanation:
The easiest way to do this lol:
Subtract 255 from 300 to get 45. Since 45 is divisible by 5 which is the average amount of cats they can take per day, count by 5 with your fingers until you reach the number five. How many fingers are you holding up? Nine. Tadaaa.