28) 1/(x+7) + 1/(x-3) = 0;

1. Combine fractions: (x-3 + x+7)/((x+7)(x-3)) = 0.

2. Simplify numerator: (2x+4)/((x+7)(x-3)) = 0.

3. Solve for x: 2x+4 = 0 -> x = -2.