中一未知數

(2-t)/4-t=(2t-3)/5

如果左邊的 -t 不是分母的一部分 , 與 (2-)/4 分開:
[(2 - t) / 4] - t = (2t - 3) / 5
(2 - t) - 4t / 4 = (2t - 3) / 5 ... 通分母
(2 - t - 4t) / 4 = (2t - 3) / 5
2 - 5t / 4 = (2t - 3) / 5
5 (2 - 5t) / 20 = 4 (2t - 3) / 20 ... 通分母
10 - 25t / 20 = 8t - 12 / 20
10 - 25t = 8t - 12 ... 左右邊分母相同可互相倍大 20 而得到抵消
8t + 25t = 10 + 12
33t = 22
t = 22/33

(2-t)/4-t=(2t-3)/5
5(2-t)=(2t-3)(4-t)
10-5t=8t-12-2t*t-3t
-2t*t+6t-22=0
t*t-3t-11=0

(2-t)/4 - t = (2t-3) /5
(2-t)/4 - (2t-3)/5 -t = 0
[(10-5t)-(8t-12)-20t]/20 = 0
(-33t + 22)/20 = 0
-33t + 22 = 0
-33t = -22
t = -22/-33 =2/3

好簡單~~

全式x4：( 2 - t ) - 4t =4 ( 2t - 3 ) / 5
2 - 5t = (8t - 12) / 5
然後又全式x5：10 - 25t = 8t - 12
22 = 33t
敢 t 咪 = 22 / 33
= 2 / 3囉~~~