\(x+x\times\frac{1}{3}\div\frac{2}{9}+x\div\frac{2}{7}=252\)
\(\Leftrightarrow x+x\times\frac{1}{3}\times\frac{9}{2}+x\times\frac{7}{2}=252\)
\(\Leftrightarrow x\left(1+\frac{1}{3}\times\frac{9}{2}+\frac{7}{2}\right)=252\)
\(\Leftrightarrow x\left(\frac{6}{6}+\frac{9}{6}+\frac{21}{6}\right)=252\)
\(\Leftrightarrow x\times\frac{36}{6}=252\)
\(\Leftrightarrow x\times6=252\)
\(\Leftrightarrow x=252\div6\)
\(\Leftrightarrow x=43\)