我想有人幫我解答這兩條數學

1) (3/4)d+12=3d
把兩邊乘4
3d+48=12d
9d=48
d=16/3或5又1/3

2) (1/3)s=-0.2(1-3s)
因為0.2=1/5,把兩邊乘15
5s= -3(1-3s)
5s=9s-3
3=4s
s=3/4

唔知啱唔啱:
1. 3d/4+12=3d
3d/4+12-3d/4=3d-3d/4
12=(4*3d)/4-3d/4
12=12d/4-3d/4
12=9d/4
12*4=9d/4*4
48=9d
48/9=9d/9
5又9分之3(5又3分之1)=d

2.唔係好識，好怕答錯:
s/3=-0.2(1-3s)
s/3=-0.2-(-0.6s)
s/3=-0.2+0.6s-0.6s
s/3-0.6s=-0.2
s/3-s/3-3*0.6s/3=-0.2
s/3-1.8s/3=-0.2
-0.8s/3=-0.2
-0.8s=-0.6
s=0.75

1
d=5 and 1/3
2
s=3/14