Решение:
а) $$1,8 \cdot y = -3,69$$
$$y = -3,69 : 1,8$$
$$y = -2,05$$
б) $$-4,6 : x = -23$$
$$x = -4,6 : (-23)$$
$$x = 0,2$$
в) $$\frac{11}{15}y + \frac{9}{10} = \frac{8}{15}$$
$$\frac{11}{15}y = \frac{8}{15} - \frac{9}{10}$$
$$\frac{11}{15}y = \frac{16}{30} - \frac{27}{30}$$
$$\frac{11}{15}y = -\frac{11}{30}$$
$$y = -\frac{11}{30} : \frac{11}{15}$$
$$y = -\frac{11}{30} \cdot \frac{15}{11}$$
$$y = -\frac{1}{2}$$