Задание 7

$$\frac{3}{2}-\frac{9}{5}=$$$$\frac{3\cdot 5}{2\cdot 5}-\frac{9\cdot 2}{5\cdot 2}=$$$$\frac{15}{10}-\frac{18}{10}=$$$$\frac{15-18}{10}=-\frac{3}{10}=-0,3$$