Question

Tìm x biết :

a) 75%x - 1/2 = một và một phần 4 

b) ( x - 2/5 ) + 7/10 = 3

Answer 1

b) ( x - 2/5 ) + 7/10 = 3

    x - 2/5 = 3 - 7/10

    x - 2/5 = 23/10

   x = 23/10 + 2/5

    x = 27/10

vậy x = 27/10

Answer 2

`75%x - 1/2 = 1 1/4`

`=> 3/4x - 1/2 = 5/4`

`=> 3/4x         = 5/4 + 1/2`

`=> 3/4x         = 7/4`

`=>     x          = 7/4 : 3/4`

`=>     x          = 7/3`

_____________________________________

`(x - 2/5) + 7/10 = 3`

`=> x - 2/5       = 3 - 7/10`

`=> x - 2/5        = 23/10`

`=> x                 = 23/10 + 2/5`

`=> x                 = 27/10`

Answer 3

\(\text{75}\%x-\dfrac{1}{2}=1\dfrac{1}{4}\)

      \(\text{ x-}\dfrac{1}{2}=\dfrac{3}{4}-\dfrac{5}{4}\)

       \(\text{ x}-\dfrac{1}{2}=-\dfrac{2}{4}\)

        \(\text{ x}=-\dfrac{2}{4}+\dfrac{1}{2}\)

         \(\text{ x}=0\)

\(---------\)

\((\text{x}-\dfrac{2}{5})+\dfrac{7}{10}=3\)

\(\text{x}-\dfrac{2}{5}=3-\dfrac{7}{10}\)

\(\text{x}-\dfrac{2}{5}=\)\(\dfrac{\text{23}}{\text{1}\text{0}}\)

       \(\text{x}=\dfrac{27}{10}\)