1／4 ＋0．4＝1／5 ＋X ,X=?

that "point" is not a point but a cross, right? that means times, isn't it?

根據1／4 ＋0．4＝1／5 ＋X

=> 1/4+ 2/5=1/5+X

=> 1/4+2/5-1/5=X

=> 1/4+1/5 =X

=> 5/20+4/20=9/20=X

驗算: X=9/20 , 代入算式

1/4+0.4=1/5+9/20

=> 13/20=13/20

答案:X=9/20

1／4 ＋0．4＝1／5 ＋X
5+8=4+20x
9=20x
x=9/20
Therefore x=9/20

1/4+0.4=1/5+X 1/4+0.4=1/5+X

這樣較簡單 這樣較複雜
1/4=0.25 1/5=0.2 0.4=2/5


0.25+0.4=0.2+X 1/4+2/5=1/5+X

0.65=0.2+X =13/20=1/5+X

X=0.65-0.2 X= 13/20-5/1

X=0.45(9/20) X=9/20(0.45)

1/4 (0.25) + 0.4= 1/5(0.2)+ X
0.65= 0.2+x
X=0.45 (9/20)

你那到底是0*4
還是0.4