\(\frac{x+4}{5}+\frac{x+2}{7}=\frac{x+5}{4}+\frac{x+7}{2}\)
\(\Rightarrow\left(\frac{x+4}{5}+1\right)+\left(\frac{x+2}{7}+1\right)=\left(\frac{x+7}{2}+1\right)+\left(\frac{x+2}{7}+1\right)\)
\(\Rightarrow\frac{x+9}{5}+\frac{x+9}{7}=\frac{x+9}{4}+\frac{x+9}{2}\)
\(\Rightarrow\frac{x+9}{2}+\frac{x+9}{4}-\frac{x+9}{7}-\frac{x+9}{5}=0\)
\(\Rightarrow\left(x+9\right)\left(\frac{1}{2}+\frac{1}{4}-\frac{1}{5}-\frac{1}{7}\right)=0\)
vì \(\frac{1}{2}+\frac{1}{4}-\frac{1}{5}-\frac{1}{7}\ne0\Rightarrow x+9=0\)
=>x=-9
vậy x=-9