d: \(\Leftrightarrow15\left(x-3\right)+2\left(4x-10.5\right)=12\left(x+1\right)+120\)
\(\Leftrightarrow15x-45+8x-21=12x+12+120\)
\(\Leftrightarrow23x-66-12x-132=0\)
=>11x-198=0
hay x=18
e: \(\Leftrightarrow\left[{}\begin{matrix}3x-2=0\\\dfrac{2\left(x+3\right)}{7}=\dfrac{4x-5}{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\10\left(x+3\right)=7\left(4x-5\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\10x+30-28x+35=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\65-18x=0\end{matrix}\right.\Leftrightarrow x\in\left\{\dfrac{2}{3};\dfrac{65}{18}\right\}\)
f: \(\Leftrightarrow\left(x-3\right)\cdot\left(21x+6+10-30x\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(16-9x\right)=0\)
hay \(x\in\left\{3;\dfrac{16}{9}\right\}\)
