5分之4+x-五分之4乘x等于20分之21 \(^o^)/~\(≧▽≦)/~

5分之4+x-五分之4乘x等于20分之21 \(^o^)/~\(≧▽≦)/~
5分之4+x-五分之4乘x等于20分之21 \(^o^)/~\(≧▽≦)/~

5分之4+x-五分之4乘x等于20分之21 \(^o^)/~\(≧▽≦)/~
4/5+x-(4/5)x=21/20
4/5+[x-(4/5)x]=21/20
4/5+(1/5)x=21/20
(1/5)x=21/20-4/5
(1/5)x=1/4
x=1/4×5
x=5/4