200bilete la pretul de 4lei respectiv 6lei ....notam cu x nr. biletelor xe4lei asta rezulta ca (200-x) =nr biletelor de 6 lei 4×X+6×(200-x)=980 4×X+6×200-6×X=980 4X+1200-6X=980(facem plus 6X) 4X+1200=980+6X(facem minus 4X) 1200=980+2X 2X=1200-980 2X=220 X=220:2 =110