primul:4×s+1×c+10×g=26,5
al doilea:3×s+1×c+7×g=20,2
al 3-lea:1×s+1×c+1×g=?
prin scadere=>26,5-20,2=1×s+3×g=> 6,3=pretul unui sandvis si a 3 gogosi
6,3×4=25,2=12×g+4×s
26,5=10×g+4×s+1×c
=> 1×c-2×g=1,3 lei
=>1×c=2×g+1,3
=>al trilea cumpara :2×g+1,3+1×g+1×s=3×g+1×s+1,3=6,3+1,3=7,6lei
Sper ca s-a-nteles :))