50÷(x-0.4)×100=2660 两边同时除以100得
50÷(x-0.4)=26.6 两边同时乘以x-0.4得
26.6(x-0.4)=50
26.6x-10.64=50
26.6x=50+10.64
26.6x=60.64
2660x=6064
665x=1516
x=665分之1516
50除以(X-0.4)乘以100等于2660
50÷(X-0.4)=2660÷100
50÷(X-0.4)=26.6
X-0.4=50÷26.6
X=50÷26.6+0.4
X=2又1165分之186