=s(-30 1/2+29 4/13)+t(409 1/9-407 1/5)=
= -s(30 1/2-29 4/13)+t(2+(1/9-1/5)=
=-s(1+1/2-4/13)+t(2+(5-9)/45)=-s(1+(13-8)/26)+t(2-4/45)=
= -s(1 5/26)+t*(1 41/45)=2 3/5*31/26+9/43*86/45=
=13/5*31/26+2/5=31/5+2/5=33/5=6.6
