a)
\(\frac{3}{4}\) = \(\frac{3.5}{4.5}\) = \(\frac{15}{20}\)
\(\frac{2}{5}\) = \(\frac{2.4}{5.4}\) = \(\frac{8}{20}\)
b)
\(\frac{11}{36}\)
\(\frac{5}{12}\) = \(\frac{5.3}{12.3}\) = \(\frac{15}{36}\)
c)
\(\frac{2}{3}\) = \(\frac{2.4.5}{3.4.5}\) = \(\frac{40}{60}\);
\(\frac{3}{4}\) = \(\frac{2.3.5}{4.3.5}\) = \(\frac{45}{60}\);
\(\frac{4}{5}\) = \(\frac{4.3.4}{5.3.4}\) = \(\frac{48}{60}\);