Đáp án:
$a,$ `20 : x + 19 = 14`
`-> 20 : x = 14 - 19`
`-> 20 : x = -5`
`-> x = 20 : (-5)`
`-> x = -4`
Vậy `x = -4`
$b,$ `x . (-2) - 9 : (-3) = (2 - 7)`
`-> -2x - (-3) = -5`
`-> -2x + 3 = -5`
`-> 2x = -5 - 3`
`-> 2x = -8`
`-> x = -8 : 2`
`-> x = -4`
Vậy `x = -4`
`c, 6 |2 - x| = |-15 + 3|`
`-> 6 |2 - x| = |-12|`
`-> 6 |2 - x| = 12`
`-> |2 - x| = 12 : 6`
`-> |2 - x| = 2`
`->` \(\left[ \begin{array}{l}2-x=2\\2-x=-2\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=2-2\\x=2-(-2)\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=0\\x=4\end{array} \right.\)
Vậy `x=0` hoặc `x = 4`
