\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(+x\times\frac{1}{8}\)\(=\frac{21}{24}\)
\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{21}{24}\)\(\div\frac{1}{8}\)
\(x\times\frac{1}{2}\)\(+x\times\frac{1}{4}\)\(=\frac{168}{24}\)
\(x\times\frac{1}{2}\)\(=\)\(\frac{168}{24}\div\frac{1}{4}\)
\(x\times\frac{1}{2}\)\(=\frac{1344}{24}\)
\(x=\frac{1344}{24}\div\frac{1}{2}\)
\(x=112\)