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70 linguri si 120 furculite costa 450 lei; 70 linguri si 130 de furculite costa 470 lei. cat costa o lingura? dar o furculita?

Răspuns :

70 linguri.....130 furculite=470
70 linguri......120 furculite=450
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/                      10f=20=>f=20:10=>f=2 lei costa o furculita
70l+130x2=470
70l=470-260
l=210:70
l=3 lei costa o lingura
[tex]70l+120f=450 \\ \\ 70l+130f=470 \\ \\ 130-120=10f \\ \\ 470-450=20 \\ \\ 1f=20/10=2 \\ \\ 2*120=240 \\ \\ 70l=450-240=210 \\ \\ 1l=210:70=3[/tex]