Tìm số nguyên x biết: (x + 30) : (-45) = -4

* Hướng dẫn giải

$\begin{array}{l}\left(\mathrm{x}+\text{3}0\right):\left(-\text{45}\right)=-\text{ 4}\\ \mathrm{x}+\text{3}0=-\text{4}.\left(-\text{45}\right)\\ \mathrm{x}+\text{3}0=\text{ 18}0\\ \mathrm{x}=\text{18}0–\text{ 3}0\\ \mathrm{x}=\text{15}0\end{array}$