答:
1)
1/3x+1/2(1/3x+980)+980=x
(1+1/2)×(x/3+980)=x
(3/2)×(x/3+980)=x
x/2+1470=x
x-x/2=1470
x/2=1470
x=2940
2)
0.3x-0.1/0.2+1=0.06+0.01/0.03
0.3x-0.5+1=0.06+1/3
0.3x+0.5=0.06+1/3
0.3x=-0.46+1/3
x=-0.46/0.3+1/0.9
x=-13.8/9+10/9
x=-3.8/9
x=-19/45
3)
-4x+9=-3(2x-5)
-4x+9=-6x+15
6x-4x=15-9
2x=6
x=3
4)
15-0.01x/0.6-1/2=0.1x/9
15-x/60-0.5=x/90
1.5x/90+x/90=14.5
2.5x=14.5×90
x=522
5)
60+(1/2+x)+96x=1500
60+0.5+97x=1500
97x=1500-60.5
97x=1439.5
x=14395/970
x=2879/194