So there is the equation x+8=3x+2.
The solution is x=3.
So these four numbers are 3,4, 10, 1 1.
(2) Party A's work efficiency is 1/20, and Party B's work efficiency is X.
There is an equation1/20+x =112.
The solution is x= 1/30.
After 7 days of cooperation, Party A and Party B still have 5/12,5/12 ÷1/30 =12.5 (days).
So it still takes 12.5 days.
(3) There are N×5/9 people in chemistry and N×4/9 people in physics.