a. $\frac{7}{9}$ x $\frac{4}{5}$ = $\frac{7 x 4}{9 x 5}$ = $\frac{28}{20}$
b. 2 $\frac{1}{4}$ x 3 $\frac{2}{5}$ = $\frac{9}{4}$ x $\frac{17}{5}$ = $\frac{9 x 17}{4 x 5}$ = $\frac{153}{20}$
c. $\frac{1}{5}$ : $\frac{1}{5}$ = $\frac{1}{5}$ x $\frac{5}{1}$ = 1
d. 1 $\frac{1}{5}$ : 1 $\frac{1}{3}$ = $\frac{6}{5}$ x $\frac{3}{4}$ = $\frac{18}{20}$