17) $$5\frac{1}{7}(y-7)-3\frac{3}{7}(14-y) =$$
$$\frac{36}{7}(y-7) - \frac{24}{7}(14-y) =$$
$$\frac{36}{7}y - \frac{36}{7} \cdot 7 - \frac{24}{7} \cdot 14 + \frac{24}{7}y =$$
$$\frac{36}{7}y - 36 - 48 + \frac{24}{7}y =$$
$$\frac{60}{7}y - 84 =$$
$$8\frac{4}{7}y - 84$$
Ответ: $$8\frac{4}{7}y - 84$$