(a) \(\frac{5}{8} of 2\frac{1}{2} - \frac{3}{4} \div \frac{3}{5}\)
= \((\frac{5}{8} \times \frac{5}{2}) - (\frac{3}{4} \div \frac{3}{5})\)
= \((\frac{25}{16}) - (\frac{5}{4})\)
= \(\frac{25 - 20}{16}\)
= \(\frac{5}{16}\)
(b)



\(V = \frac{1}{3} \times A \times h = \frac{1}{3} \pi r^{2} h\)
\(\therefore \frac{1}{3} \times 154 \times h = \frac{1}{3} \times \pi \times r^{2} \times h\)
Comparing the two equations,
\(154 = \frac{22}{7} \times r^{2}\)
\(r^{2} = \frac{154 \times 7}{22}\)
\(r^{2} = 49\)
\(\therefore r = 7 cm\).