设甲每小时x 乙y个
3y-400=0.5x
7y+4200=4.5x
x=6y-800
7y+4200=4.5(6y-800)
7y+4200=27y-3600
27y-7y=4200+3600
20y=7800
y=390
x=6x390-800=1540
设甲每小时x 乙y个
3y-400=0.5x
7y+4200=4.5x
x=6y-800
7y+4200=4.5(6y-800)
7y+4200=27y-3600
27y-7y=4200+3600
20y=7800
y=390
x=6x390-800=1540