1)2m/(m+4)+16/(m²-4m+16)-(m²-20m²)/(m+4)(m²-4m+16)=
=[2m(m²-4m+16)+16(m+4)-(m³-20m²)]/(m+4)(m²-4m+16)=
=(2m³-8m²+32m+16m+64-m³+20m²)/(m+4)(m²-4m+16)=
=(m³+12m²+48m+64)/(n+4)(m²-4m+16)=(m+4)³/(m+4)(m²-4m+16)=
=(m+4)²/(m²-4m+16)
2)(m+4)-12m/(m+4)=(m²+8m+16-12m)/(m+4)=(m²-4m+16)/(m+4)
3)(m+4)²/(m²-4m+16) * (m²-4m+16)/(m+4)=m+4
4)(m+4):(m+4)=1