x÷15+0.4＝x÷12－0.1x÷15=x÷12－0.1-0.4x÷15=x÷12-0.5x÷15×60=(x÷12-0.5)×604x=5x-30x=30x+x÷3+2x－30＝180 x+x÷3+2x=180+30x+x÷3+2x=2103x+x÷3=210(3x+x÷3)×3=210×39x+x=63010x=630x=63
