Assuming that 100 people are big monks, then * * * needs 300 steamed buns, which is 300- 140 = 160 (one) more than the actual situation. At present, young monks are replaced by big monks, and every time they change buns, there will be fewer.
3- 1 = 2 (a), because 160÷2=80, there are 80 young monks and 80 big monks.
100-80 = 20 (person).