Lời giải:
$\frac{12}{11}\times \frac{36}{144}\times \frac{121}{72}$
$=\frac{12}{11}\times \frac{1}{4}\times \frac{11\times 11}{12\times 6}$
$=\frac{12}{11}\times \frac{11}{12}\times \frac{11}{6}\times \frac{1}{4}$
$=\frac{11}{6}\times \frac{1}{4}=\frac{11}{24}$