`\text{a)}`
`7(x - 2) - 5(x - 4) = 28`
`7(x - 2) = 28 + 5(x - 4)`
`7x - 14 = 28 + 5x - 20`
`7x - 5x = 28 - 20 + 14`
`2x = 22`
`x = 11`
`\text{b)}`
`(x - 3)^2 - 48 = -12`
`(x - 3)^2 = -12 + 48`
`(x - 3)^2 = 36`
`(x - 3)^2 = 6^2`
`⇒ x -3 = 6 → x = 9` `\text{hoặc}` `x -3 = -6 ⇒ x = -3`
`\text{c)}`
`-7 -2x = -37 - (-26)`
`-7 - 2x = -11`
` 2x = -7 +11`
`2x = 4`
`x = 2`