0.3:0.5=x+1:2x-1
0.3:0.5=(x+1):(2x-1)
0.3(2x-1)=0.5(x+1) (内项积等于外项积)
0.6x-0.3=0.5x+0.5
0.6x-0.5x=0.5+0.3
0.1x=0.8
x=0.8÷0.1
x=8