Resposta :
[tex]x=\dfrac{x}{3}+\dfrac{3}{4}\times\dfrac{x}{3}+120\Longrightarrow x=\dfrac{x}{3}+\dfrac{x}{4}+120\\\\
\dfrac{3\cdot4\cdot x}{3\cdot4}=\dfrac{4\cdot x}{3\cdot4}+\dfrac{3\cdot 4}{3\cdot4}+\dfrac{3\cdot4\cdot120}{3\cdot4}\\\\
12x=4x+3x+1440\\\\
12x-7x=1440\\\\
5x=1440\\\\
x=\dfrac{1440}{5}\\\\
x=288\;\text{reais}[/tex]