You can put this solution on YOUR website! common denominator is (n+3)(n+2)
The numerator will be n^2+3n+2-2n(n+2)= -n^2-n+2=-(n^2+n-2)=-(n+2)(n-1)
The (n+2) will cancel numerator and denominator,
so the answer is
-(n-1)/(n+3)
Check with n=4
30/42-8/7=-18/42 or -3/7
-(3)/7