①17x+3.4=27.2
②2.5x-6=18.5
③2.1+3x=12.6
④2.7x-0.7x=20
⑤5.6x+4x=17.28
⑥5(x+4.1)=36.5
28.7-14.7+1.4
21÷3.5+21÷1.5
56.14÷3.5÷2
6.17×13.6+1.36×( )(填数使它可简便计算)
4.2x-2.6x=4.88
5(20x+1.5)=17.5