3.5x-2x=9
9.6-5x=2.1
1.6x-1.5=2.1
①20+x=35 ②3x+6x=81 ③8x-24=80
2x+5.4=18.9 2x-2.8=9.96 (x-0.8)×4=7.2
2x+5=17 3(x-2)=12
① ② ③
⑴6x-9=33 ⑵y+3y=28.4