You can put this solution on YOUR website! From
3 / (x^2 + 4x + 3) - 1 / (x^2 - 9)
we factor in order to find the lowest common denominator and get
3 / (x + 3)(x + 1) - 1 / (x - 3)(x + 3)
and the LCD would be (x+3)(x-3)(x+1)
Now convert each fraction
3(x - 3) / (x+3)(x-3)(x+1) - (x + 1) / (x+3)(x-3)(x+1)
= (3x - 9 - x - 1) / (x+3)(x-3)(x+1)
= (2x - 10) / (x+3)(x-3)(x+1)