Solve the Inequality and Give the Solution Set in Set $$\frac { x + 21 } { x + 7 } < 3$$

Solve the inequality and give the solution set in set builder notation.
- $$\frac { x + 21 } { x + 7 } < 3$$

A) $$\{ x \mid x < 0 \text { or } x > 7 \}$$
B) $$\{ x \mid - 7 < x < 0 \}$$
C) $$\{ x \mid x < - 7 \text { or } x > 0 \}$$
D) $$\varnothing$$