1/4(y+2)+1/5(y+3)+1/6(y+4)=3
两边同时乘以60
15（y+2)+12(y+3)+10(y+4)=180
15y+30+12y+36+10y+40=180
15y+12y+10y=180-30-40-36
37y=74
y=2
2.5（x+3)-5.5(1-x)=3[(2x-2)+4]
2.5x+7.5-5.5+5.5x=3(2x-2+4)
8x+2=3(2x+2)
8x+2=6x+6
8x-6x=6-2
2x=4
x=2