1.(4/3)/(7/5)=20/21 50/(1-20/21)=1050(m)
2.(8/7)/(3/4)=32/21 66/(32/21-1)=126(步)
3.4*(5/3)=20/3 20/(7-20/3)=60m
4.10/20/2=1/4h 1/4*(20+50)=17.5km
5.24/(4-3)*3=72km/h 72*8=576km
6.5-4*6/5=1/5 10/(1/5)*(4+5)=450km
7.设有X工人 但工效为a
则 3/4x*1/2+7/12x*1/2=(1/4x*1/2+5/12x*1/2+4)*1.5
x=36 答;36人
8.350+400-500-100=150(个) 150/(75-25)%=300(个)
400-300*75%=175(个) 100-300*25%=25(个)
答:黑175白25
9.(3-1)/(5-3)=1 3*[5/(5+1)]=2.5h