Suppose a mouse eats one serving of food a day, then 1000 mice eat 600,000 servings in 600 days, and an elephant eats 50,000 servings a day. A T-elephant is 50000t a day, and a hundred mice are 100,50,000t/100, which is 500t a day (in this case, if the physical quantity is wrong, it is purely a clerical error).

Algebra exercise: Give an elephant's food to a mouse for X days. Get 12x= 1000*600, get x=50000, and then you can set T elephant's food for one hundred mice to eat for y days, get tx= 100y, get 500t=y (of course, after setting X, you can also use the arithmetic method directly: 5000.