Suppose you can reduce x hours and move y bricks per hour per person.

Column equation 25*6*y=30*(6-x)*y

X= 1

2

First prize: 84* 1 1/42=22.

Second prize: 84* 15/42=30.

Third prize: 84* 16/42=32

three

Blood quality x

7:20=x:40 gives x= 14.