Lg5=a;lg3=b;log30(8)=?
log30(8)=lg8/lg30=3lg2/(lg5+lg2+lg3)=
3lg2/(a+b+lg2)
lg2=?
lg5=a;lg(5•2)/2=(lg5+lg2)/lg2=a
lg5+lg2=alg2
lg5=lg2*(a-1)
lg2=lg5/(a-1)=a/(a-1)
lg2=a/(a-1)
log30(8)=3lg2/(a+b+lg2)=
3a/(a-1)*1/(a+b+a/(a-1))
3a/(a-1)*((a-1)/((a+b)(a-1)+a)=
3a/((a+b)(a-1)+a)=
3a/(a^2-a+ab-b+a)=
3a/(a^2+ab-b)