A^2+2a-3/a^2+3a-10: a^2+7a+12/a^2-9a+14 решите )

(aˇ2+2a-3)/(aˇ2+3a-10) : (aˇ2+7a+12)/(aˇ2-9a+14)=
=(a+3)(a-1)/(a+5)(a-2): (a+4)(a+3)/(a-2)(a-7)=
=(a+3)(a-1)/(a+5)(a-2) . (a-2)(a-7)/(a+4)(a+3)=
=(a-1)/(a+5) . (a-7)/(a+4)=(a-1)(a-7)/(a+5)(a+4)=
=(aˇ2-8a+7)/(aˇ2+9a+20)