б) √(49/729) + √(9/16) =

\(\sqrt{\frac{49}{729}}=\frac{7}{27}\), \(\sqrt{\frac{9}{16}}=\frac{3}{4}\).

\(\frac{7}{27}+\frac{3}{4}=\frac{28}{108}+\frac{81}{108}=\frac{109}{108}\).

Ответ: \(\frac{109}{108}\)