求未知数x147÷5x=9.8 160×25％-1.3x=17.9 2/3x＋1/4x=3.3 0.8×（x-0.2）=

147÷5x=9.8
5x=147÷9.8
x=15÷5
x=3
160×25％-1.3x=17.9
40-1.3x=17.9
1.3x=40-17.9
x=22.1÷1.3
x=17
2/3x＋1/4x=3.3
（2/3+1/4）x=3.3
11/12x=3.3
x=3.3÷11/12
x=3.6
0.8×（x-0.2）=1
0.8x-0.16=1
0.8x=1+0.16
x=1.16÷0.8
x=1.45
2％x×15+1/2=11
0.3x+0.5=11
0.3x=11-0.5
x=10.5÷0.3
x=3.5
5/x-6/x=0.4
(5-6)/x=0.4
-1/x=0.4
0.4x=-1
x=-1÷0.4
x=-2.5