Question 21674
well first off factor x^2-100 into (x+10)(x-10) you are left with <br>

x/((x+10)(x-10)) * (9x(x+10))/(x+3)<br>

the x+10's cancel leaving you with <br>

x/x-10 * 9x/x+3<br>

now just simplify<br>

9x(x)/(x-10)(x+3)
9x^2/(x^2+3x-10x-30)
9x^2/(x^2-7x-30)