a)y+30%y=1,3

<=>1,3y=1,3

<=>y=1.

b)y+25%y=1/2

<=>1,25y=1/2

<=>y=0,4

y=-1,3/(1+30%) tự tính :v

y= 1/2 : (1-25%) tự tính :3

sao 1+30% vay bn

a,y+30%y=-1,3

  y+3/10y=-1,3

y(1+3/10)=-1,3

y(10/10+3/10)=-1,3

13/10y=-13/10

y=-13/10:13/10

y=-1

Vậy y=-1

b,y-25%y=1/2

y-1/4y=1/2

y(1-1/4)=1/2

y(4/4-1/4)=1/2

3/4y=1/2

y=1/2:3/4

y=3/8

Vậy y=3/8

a/ y + 30%y = -1,3  

   => y + \(\frac{3}{10}\)y = -1,3

   => \(\frac{13}{10}\)y = -1,3

   => y = -1

b/ y - 25%.y = \(\frac{1}{2}\)

   => y - \(\frac{1}{4}\)y = \(\frac{1}{2}\)

   => \(\frac{3}{4}\)y = \(\frac{1}{2}\)  => y = \(\frac{2}{3}\)

a)\(y+30\%y=-1,3\)

\(y\frac{130}{100}=\left(-\frac{130}{100}\right)\)

\(y=\left(-\frac{130}{100}\right):\frac{130}{100}\)

\(y=-1\)

b)\(y-25\%y=\frac{1}{2}\)

\(y\frac{75}{100}=\frac{50}{100}\)

\(y=\frac{50}{100}:\frac{75}{100}\)

\(y=\frac{2}{3}\)

a, y + 30%y = -1,3

 1.y + 30/100y = -13/10

 1.y + 3/10y  = -13/10

(1 + 3/10). y = -13/10

13/10 .y = -13/10

           y = -13/10 : 13/10

           y = -13/10 . 10/13

           y = -1

b, y - 25%y = 1/2

   1.y - 25/100.y = 1/2

   1.y - 1/4.y = 1/2

   (1 - 1/4) y = 1/2

    3/4 .y = 1/2

           y = 1/2 : 3/4

           y = 1/2 . 4/3

           y = 2/3

câu c mik chưa nghĩ ra

\(a)\) \(y+30\%=\dfrac{-1}{3}\)

\(\Rightarrow y+\dfrac{3}{10}=\dfrac{-1}{3}\)

\(\Rightarrow y=\dfrac{-19}{30}\)

Vậy ...

\(b)\) \(y-25\%y=\dfrac{1}{2}\)

\(\Rightarrow1y-\dfrac{1}{4}y=\dfrac{1}{2}\)

\(\Rightarrow y\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(\Rightarrow y\dfrac{3}{4}=\dfrac{1}{2}\)

\(\Rightarrow y=\dfrac{2}{3}\)

Vậy .....

a, \(y+30\%=-1,3\)

\(\Rightarrow y=-\dfrac{13}{10}-\dfrac{3}{10}\)

\(\Rightarrow y=\dfrac{-8}{10}\)

b, \(y-25\%y=\dfrac{1}{2}\)

\(\Rightarrow y\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{3}{4}y=\dfrac{1}{2}\)

\(\Rightarrow y=\dfrac{1}{2}:\dfrac{3}{4}\)

\(\Rightarrow y=\dfrac{2}{3}\)

a) 0,5 x - \(\frac{2}{3}\)x = \(\frac{7}{12}\)

   x . ( 0,5 - \(\frac{2}{3}\)) = \(\frac{7}{12}\)

   x .  \(\frac{-1}{6}\)        = \(\frac{7}{12}\)

   x                         = \(\frac{7}{12}\): \(\frac{-1}{6}\)

   x                          = \(\frac{-7}{2}\)

b) x : \(\frac{25}{3}\)      = -25 

    x                     = -25 . \(\frac{25}{3}\)

     x                    = \(\frac{-625}{3}\)

c) 5,5 x = \(\frac{13}{15}\)

          x = \(\frac{13}{15}\): 5,5

           x = \(\frac{26}{165}\)

d) (\(\frac{3x}{7}\)+ 1 ) : ( -4) = \(\frac{-1}{28}\)

   ( \(\frac{3x}{7}\)+ 1 )           = \(\frac{-1}{28}\). ( -4)

 \(\frac{3x}{7}\)+ 1                 = \(\frac{1}{7}\)

 \(\frac{3x}{7}\)                       = \(\frac{1}{7}\)- 1

  \(\frac{3x}{7}\)                      = \(\frac{-6}{7}\)

=> x = -2

e) y + 30% y =  -1,3

   y + \(\frac{3}{10}\)y = -1,3

  y . ( 1 + \(\frac{3}{10}\)) = -1,3

y .       \(\frac{13}{10}\)     = -1,3

y                          = -1,3 : \(\frac{13}{10}\)

y                          = -1

g) y - 25% y = \(\frac{1}{2}\)

    y - \(\frac{1}{4}\)y = \(\frac{1}{2}\)

    y . ( 1 - \(\frac{1}{4}\)) = \(\frac{1}{2}\)

    y   . \(\frac{3}{4}\)  = \(\frac{1}{2}\)

     y                = \(\frac{1}{2}\): \(\frac{3}{4}\)

     y                  = \(\frac{2}{3}\)

ai tốt bụng thì tk cho mk nha, mk đg âm điểm đây huhu

ai làm đc mìh sẽ bảo bn bè tíck cho