a) $$1 \frac{1}{2} = \frac{3}{2} = \frac{3 \cdot 36}{2 \cdot 36} = \frac{108}{72};$$
б) $$2 \frac{2}{3} = \frac{8}{3} = \frac{8 \cdot 24}{3 \cdot 24} = \frac{192}{72};$$
в) $$3 \frac{3}{4} = \frac{15}{4} = \frac{15 \cdot 18}{4 \cdot 18} = \frac{270}{72};$$
Ответ: а) 108/72, б) 192/72, в) 270/72