(4b+9)/6b+(2b-3)/6b=(4b+9+2b-3)/6b=(6b+6)/6b=1+1/b
a/(a-3)+3/(3-a)=a/(a-3)-3/(a-3)=(a-3)/(a-3)=1
(q+2)/(q-2)-(6-q)/(q-2)=(q+2-6+q)(q-2)=(2q-4)/(q-2)=2(q-2)/(q-2)=2
m^2/(m-n)-n^2/(m-n)=(m^2-n^2)(m-n)=((m-n)(m+n))/(m-n)=m+n
(x^2+1)/(x-3)^2-5x/(x-3)^2+(8-x)/(x-3)^2=(x^2+1-5X+8-x)/(x-3)^2=(x^2-6x+9)/(x-3)^2=(x-3)^2/(x-3)^2=1