Решение:

1) $$z_1 = 4 - 2i, z_2 = 3 + 8i$$

$$z_1 - z_2 = (4 - 2i) - (3 + 8i) = 4 - 2i - 3 - 8i = (4 - 3) + (-2 - 8)i = 1 - 10i$$

Ответ: $$1 - 10i$$

2) $$z_1 = \frac{5}{6} + \frac{3}{4}i, z_2 = \frac{5}{6} - \frac{1}{4}i$$

$$z_1 - z_2 = (\frac{5}{6} + \frac{3}{4}i) - (\frac{5}{6} - \frac{1}{4}i) = \frac{5}{6} + \frac{3}{4}i - \frac{5}{6} + \frac{1}{4}i = (\frac{5}{6} - \frac{5}{6}) + (\frac{3}{4} + \frac{1}{4})i = 0 + \frac{4}{4}i = i$$

Ответ: $$i$$

3) $$z_1 = \frac{7}{8} - \frac{1}{5}i, z_2 = \frac{3}{8} - \frac{1}{5}i$$

$$z_1 - z_2 = (\frac{7}{8} - \frac{1}{5}i) - (\frac{3}{8} - \frac{1}{5}i) = \frac{7}{8} - \frac{1}{5}i - \frac{3}{8} + \frac{1}{5}i = (\frac{7}{8} - \frac{3}{8}) + (-\frac{1}{5} + \frac{1}{5})i = \frac{4}{8} + 0i = \frac{1}{2}$$

Ответ: $$\frac{1}{2}$$

4) $$z_1 = 1,5 - 2,1i, z_2 = 0,5 + 0,9i$$

$$z_1 - z_2 = (1,5 - 2,1i) - (0,5 + 0,9i) = 1,5 - 2,1i - 0,5 - 0,9i = (1,5 - 0,5) + (-2,1 - 0,9)i = 1 - 3i$$

Ответ: $$1 - 3i$$

5) $$z_1 = \frac{3}{4} - \frac{1}{2}i, z_2 = \frac{1}{8} + \frac{3}{8}i$$

$$z_1 - z_2 = (\frac{3}{4} - \frac{1}{2}i) - (\frac{1}{8} + \frac{3}{8}i) = \frac{3}{4} - \frac{1}{2}i - \frac{1}{8} - \frac{3}{8}i = (\frac{3}{4} - \frac{1}{8}) + (-\frac{1}{2} - \frac{3}{8})i = (\frac{6}{8} - \frac{1}{8}) + (-\frac{4}{8} - \frac{3}{8})i = \frac{5}{8} - \frac{7}{8}i$$

Ответ: $$\frac{5}{8} - \frac{7}{8}i$$

6) $$z_1 = \frac{7}{8} - \frac{1}{2}i, z_2 = -\frac{1}{2}i$$

$$z_1 - z_2 = (\frac{7}{8} - \frac{1}{2}i) - (-\frac{1}{2}i) = \frac{7}{8} - \frac{1}{2}i + \frac{1}{2}i = \frac{7}{8} + (-\frac{1}{2} + \frac{1}{2})i = \frac{7}{8} + 0i = \frac{7}{8}$$

Ответ: $$\frac{7}{8}$$