Tìm x biết: \(\left( {525 -...

C

- Hướng dẫn giải

 \(\begin{array}{l}\ \,\left( {525 - 725} \right)x = 645 + \left( { - 15 - 30} \right) + 200\\\,\,\,\,\, - 200x = 645 + \left( { - 45} \right) + 200\\\,\,\,\,\, - 200x = 600 + 200\\\,\,\,\,\, - 200x = 800\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 800:\left( { - 200} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = - 4\end{array}\)