5x+400=2400+3x → 5x-3x=2400-400 → 2x=2000 → x=2000÷2 → x=1000
解:5x+400=2400+3x 5x-3x=2400-400 2x=2000 x=2000÷2 x=1000
5x+400=3*(800+x)解:5x+400=2400+3x5x-3x+400=24002x=2400-400x=2000÷2x=1000