a) \(x\times\frac{5}{7}=\frac{1}{4}+\frac{1}{5}\)
\(x\times\frac{5}{7}=\frac{9}{20}\)
\(x=\frac{9}{20}\div\frac{5}{7}\)
\(x=\frac{63}{100}\)
a(2) : \(2\frac{3}{3}\div x=\frac{2}{5}-\frac{1}{3}\)
\(\frac{9}{3}\div x=\frac{1}{15}\)
\(x=\frac{9}{3}\div\frac{1}{15}\)
\(x=45\)