On several mathematics problems in grade two of junior high school 1. For a project, team a will complete it in 40 days. If team B will complete it in 30 days, team a and team B will cooperate for another 20 days ① How many days does it take for engineering team B to do it alone ② The project is divided into two parts, one part of which takes X days, the other part takes y days, where XY is a positive integer and X is a positive integer

On several mathematics problems in grade two of junior high school 1. For a project, team a will complete it in 40 days. If team B will complete it in 30 days, team a and team B will cooperate for another 20 days ① How many days does it take for engineering team B to do it alone ② The project is divided into two parts, one part of which takes X days, the other part takes y days, where XY is a positive integer and X is a positive integer

1. Let B do 1 / y every day, and now let a do 1 / 40 every day
1-30/y=20*(1/40+1/y) y=100
It will take 100 days
x/30+y/100=1 10x+3y=300 y=1/3(300-10x)
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