1)(5a-10)/a²-4=5(a-2)/(a-2)(a+2)=5/a+2
2)(a²-2ab)/3a-6b=(a(a-2b))/(2(a-2b))=a/2
3) (a+3)³/5a²+15a=(a+3)³/(5a(a+3))=(a+3)²/5a
4)(m³-5m²n)/(mn²-5n)=(m²(m-5n))/(n²(m-5/n)
5)a²-6a+9/a²-9=((a-3)(a-3))/((a+3)(a-3))=(a-3)/(a+3)
6)a²-2a+1/a²-1=((a-1)(a-1))/((a+1)(a-1))=(a-1)/(a+1)