90 garoafe+30cale=690lei 70garoafe+30 cale=590 lei 30 cale=590lei-70garoafe inlocuim calele din prima adunare 90garoafe+590lei-70garoafe=690lei 20 garoafe=690lei-590lei 20garoage=100lei 1garoafa=100lei:20=5lei (garoafa) 90gatoafe+30cale=690 90×5+30calr=690lei 450 lei+30cale=690lei 30cale=690lei-450lei=240lei 1cala=240:30=8lei(o cala)