Hypothetical method

The big monk eats three, and the little monk eats 1 ÷ 3 = 1/3.

Assuming that each young monk is also three,

So 100 monks need to eat * * *: 3x100 = 300 (a steamed bread).

Compared with the actual situation, I ate too much: 300- 100 = 200 (a steamed bread).

A young monk ate too much: 3- 1/3 = 8/3 (steamed bread)

Number of young monks: 200 ÷ 8/3 = 75 (people)

Number of Big Monks: 100-75 = 25 (people)

Method 2

Grouping method

According to the meaning of the question, 1 big monk and three little monks eat four steamed buns, which means that every four steamed buns are just given to 1 big monk and three little monks. We might as well divide every four 100 steamed buns into one group, * * can be divided into: 100÷4=25 (group), and 100 monks are just divided into 25 groups. Each group must have 1 big monk and 3 small monks, so

Big monk * * * has: 1×25=25 (each)

Young monks * * * have: 3×25=75 (each)