It's simple. Let A be the number of men, B be the number of women, C be the number of children, 4a+3b+0.5c =100 (1) A+b+c =100 (2) Equation (1)-3 (2) = &

So c>8 c=(a+200)0.4 c=2/5a+80 a must be a multiple of 5.

When a=5 b= 13 c=82

a= 10 b=6 c=84

A= 15 b=- 1 c=86 is invalid.

So the answer is (1)a=5 b= 13 c=82.

(2)a= 10 b=6 c=84

When there are five big men, 13 big women and 82 children, each person moves 20, 39, 4 1 brick.

When 18 men, 6 women and 84 children each moved 4018,42 bricks.