10 dictionare..........2truse..........550 lei
10 dictionare..........5 truse.......1150 lei
----------------------------------------------------------
// 3 truse........600 lei
1 trusa=600:3
1 trusa=200 lei
10 dictionare+2x200=550
10 dictionare+400=550
10 dictionare=550-400
10 dictionare=150
1 dictionar=150:10
1 dictionar=15 lei
15x10+2x200=150+400=550