Tìm x biết rằng là: (left( {13 - 33} ight)x = 78 - 118)

* Hướng dẫn giải

Ta có:

\(\begin{array}{l}\ \ \,\left( {13 - 33} \right)x = 78 - 118\\\,\,\,\,\,\, - 20x = - 40\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = \left( { - 40} \right):\left( { - 20} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 2\end{array}\)