Can you know????

s/3=-0.2(1-3s)
s/3=-0.2-(-0.6s)
s/3=-0.2+0.6s
s=(-0.2+0.6s)3
s=-0.6+1.8s
-0.8s=-0.6
s=0.75

s=-0.6+1.8s
0.8s=0.6
s=0.75

2006-11-11 14:18:10 補充：
YES! I KNOW!

s=0.25

s/3=-0.2(1-3s)
s/3=-0.2+0.6s
s=-0.6+1.8s
0.8s=0.6
s=0.25

s/3=-0.2(1-3s)
s=-0.6(1-3s)
s=-0.6+1.8s
0.8s=0.6
s=3/4

2006-11-11 14:29:06 補充：
s/3=-0.2(1-3s)------------------------(*)checking:sub s=3/4 into (*)L.H.S.=3/4÷3 =1/4R.H.S.=-0.2[1-(3 x 3/4)] =-0.2(1-9/4) =-0.2(-5/4) =0.2 x 5/4 =1/5 x 5/4 =1/4 =L.H.S.∴My answer is not wrong是不是你的問題有錯誤?

s = [0.2(1-3s)]3
s = 0.2143