\[\boxed{\text{5.520.}}\]
\[\textbf{а)}\ \frac{2}{3}x = 1\]
\[x = \frac{3}{2}.\]
\[\textbf{б)}\ \frac{51}{62}y = 1\]
\[y = \frac{62}{51}.\]
\[\textbf{в)}\ \frac{3}{10}a = 1\]
\[a = \frac{10}{3}.\]
\[\textbf{г)}\ \frac{104}{183}b = 1\]
\[b = \frac{183}{104}.\]
\[\textbf{д)}\ \frac{7}{25}x = \frac{7}{25}\]
\[x = 1.\]
\[\textbf{е)}\ \frac{13}{6}y = \frac{13}{6}\]
\[y = 1.\]