①9x=27.27
②15x-x=1.4
③7.8x+3.2x=24.2
④8x÷12=15
⑤2x-7.2=6.8
⑥5.2+2x=16.8
5和17 14和7
24 45 70 100
1- = + = 1- = - =
- = + = + = + =
或