\(X\times20o/o+X=7,2\)

\(\Leftrightarrow\)2x+0,2=7,2

\(\Leftrightarrow\)2x     =7,2-0,2

\(\Leftrightarrow\)2x     = 7

\(\Rightarrow\) x        =7:2

\(\Rightarrow\)x        =3,5

\(40o/o\times X+X\times20o/o=72\)

\(\Leftrightarrow0,4\times X+X\times0,2=72\)

\(\Leftrightarrow X\times\left(0,4+0,2\right)=72\)

\(\Leftrightarrow X\times0,6=72\)

\(\Rightarrow X=72:0,6\)

\(\Rightarrow X=120\)

40%*x+x*20%=72

-> 0,4x+ 0,2 x= 72

-> 0,6 x= 72

-> x=120

x + 20% * x = 7.2

x +1/5 * x = 7.2

x * ( 1 + 1/5 ) = 7.2

x * 1.2 = 7.2

x = 7.2 : 1.2

x = 6

40% * x + x * 20% = 72

2/5 * x + x * 1/5 = 72

( 2/5 + 1/5 ) * x = 72

0.6 * x = 72

x = 72 : 0.6

x = 120

 40/100 x X + X x 20/100 = 72

 2/5 x X + X x 1/5 = 72

 X x ( 2/5 + 1/5 ) = 72

X x 3/5 = 72

X = 72 : 3/5

X = 120

Trả lời :

40%*X+X*20%=72

\(40\%\) \(.\)\(x\) \(+\)  \(x\) \(.\) \(\frac{20}{100}\)\(=\)\(72\)

\(\frac{40}{100}\)\(.\)\(x\)\(+\)\(x\)\(\frac{1}{5}\)\(=\)\(72\)

\(x\)\(.\)\(\left(\frac{2}{5}+\frac{1}{5}\right)\)\(=\)\(72\)

 \(x\)\(.\)\(\frac{3}{5}\)\(=\) \(72\)

\(x\)\(=\) \(72\)\(:\)\(\frac{3}{5}\)

\(x\)\(=\) \(120\)

40% * X + X * 20% = 72

X * (40% + 20%) = 72

X * 60% = 72

X * 0,6 = 72

X = 72 : 0,6

X = 120

a)x=45

b)x=270

a) \(40\%\times x+x\times20\%=72\)

       \(\left(40\%+20\%\right)\times x=72\)

                             \(60\%\times x=72\)

                                \(0,6\times x=72\)

                                             \(x=72:0,6\)

                                              \(x=120\)

b) \(x-20\%\times x=216\)

    \(x\times\left(1-20\%\right)=216\)

                   \(x\times80\%=216\)

                      \(x\times0,8=216\)

                                    \(x=216:0,8\)

                                     \(x=270\)

a, X + 20% x  X = 7,2

     X + 1/5 x X = 7,2

    X + 1/5 x X + 1 = 7,2

     X . ( 1/5 + 1 ) = 7,2

       X . 1,2 = 7,2

      X = 7,2 : 1,2

       X = 6

      Vậy X =6

Dap an ; x = 6 

      OK ? Bai minh lam giong may ban do .

a) X=6

b) X=12,3

c) X=120

d) X= 270

a) x * (1 + 20/100) = 7,2

   x * 6/5 = 72/10

   x = 72/10 : 6/5 = 6

b) x *(40/100 + 20/100 ) = 72

  x*(60/100) = 72

  x = 72 : 60/100 = 120

cách làm đó bạn, ai thấy đúng thì ủng hộ 

x*1+x*1/5=36/5

x*(1+1/5)=36/5

x*6/5=36/5

x=36/5:6/5

x=6

b,tương tự câu a

bn ơi còn cách nào nhanh hơn ko