Add or subtract the fractions with common denominators.

$$\frac{3}{7} + \frac{2}{7} = \frac{3+2}{7} = \frac{5}{7}$$

The sum is $\boxed{\frac{5}{7}}$.

$$\frac{1}{2} + \frac{0}{2} = \frac{1+0}{2} = \frac{1}{2}$$

The sum is $\boxed{\frac{1}{2}}$.

$$\frac{10}{4} + \frac{2}{4} = \frac{10+2}{4} = \frac{12}{4}$$

Simplify the fraction:

$$\frac{12}{4} = 3$$

The sum is $\boxed{3}$.

$$\frac{12}{4} - \frac{6}{4} = \frac{12-6}{4} = \frac{6}{4}$$

Simplify the fraction by dividing the numerator and denominator by 2:

$$\frac{6}{4} = \frac{3}{2}$$

The difference is $\boxed{\frac{3}{2}}$.

$$\frac{7}{2} - \frac{3}{2} = \frac{7-3}{2} = \frac{4}{2}$$

Simplify the fraction:

$$\frac{4}{2} = 2$$

The difference is $\boxed{2}$.