Bài 5.
a/$\frac{4}{5}$ = $\frac{12}{15}$ = $\frac{20}{25}$ = $\frac{48}{60}$
b/$\frac{75}{100}$ = $\frac{15}{20}$ = $\frac{225}{300}$ = $\frac{750}{1000}$
c/0 = $\frac{0}{9}$ = $\frac{0}{2006}$
d/1 = $\frac{91}{91}$ = $\frac{48}{48}$ = $\frac{2006}{2006}$
