Tìm x a`)``x . {15}/{28} = 3/4` b`)`` 4/5 x - 2/3x = {7}/{12}` c `)`x : 16/5 = 3/2 d`)``{-39}/{x} = {26}/{-48}

a`)``x . {15}/{28} = 3/4`
              `x = 3/4 : {15}/{28}`
              `x = 3/4 × {28}/{15}`
              `x = {84}/{60}`
              `x = 7/5`

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b`)`` 4/5 x - 2/3x = {7}/{12}`
      `x.(4/5 - 2/3) = 7/12`
      `x.2/15 = 7/12 `
      `x = 7/12 : 2/15 `
      `x = 7/{12}.15/2 `
      `x = 105/24 `
      `x = 35/8`

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c`)``x : 16/5 = 3/2 `

     `x = 3/2 . 16/5 `

    `x = 48/10`

    `x = 24/5`

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d`)``{-39}/{x} = {26}/{-48}`

    `x . 26 = (-39)(-48)`

    `x . 26 = 1872`

    `x = {1872}/{26}`

    `x = 72`