3
=-1,6n-76 27/72*m+78 8/72*m=-1,6n-76 27/72*m+77 80/72*m=
=-1,6n+1 53/72*m
m=24/25,n=10
-1,6*10+125/72*24/25=-16+1 2/3=-14 1/3
4
=(29 4/13-30 1/2)*s+(409 1/9-407 1/5)*t=
=(29 8/26-30 13/26)*s+(409 5/45-407 9/45)*t=-1 5/26*s+1 41/45*t
s=-2,6;t=9/43
-31/26*(-26/10)+86/45*9/43=3,1+0,4=3,5