Suppose they are all big monks.

( 100*3- 140)/(3- 1)

=(300- 140)/2

= 160/2

=80 (person) ... Little monk

100-80=20 (person) ... Little monk

This is a profit and loss problem.

(9+6)/(5-4)

= 15/ 1

= 15 (person) ... number of people

15*4+9

=60+9

=69 (grains) ... the number of sweets