①200x+50(22-x)=1400
4个回答

① 200x+50(22-x)=1400

200x+1100-50x=1400

150x+1100-1100=1400-1100

150x÷150=300÷150

x=2

② 10x-5(10-x)=55

10x-50+5x=55

15x-50+50=55+50

15x÷15=105÷15

x=7

③ 3(x+5)+2x=5×6

3x+15+2x=30

5x+15-15=30-15

5x÷5=15÷5

x=3