Răspuns: 30 zeds= 1/5
15 zeds= 2/3
900 bilete= 5/5
1/5=900:5
1/5=180
30 zeds= 180 bilete
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15 zeds= 2/3
900 bilete= 3/3
1/3=900:3
1/3=300
2/3=300x2
2/3=600
15 zeds= 600 bilete
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10 zeds=900-(180+600)
10 zeds=900-780
10 zeds=120 bilete
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