Question

3cornuri...5paini=2300g ;4cornuri...2 paini=1200g;1corn...1paine=?g

Answer 1

3 cornuri...5 paini...2300g
4 cornuri...2 paini...1200g
Inmultim prima relatie cu 4, iar pe cea de a doua cu 3:
12 cornuri...20 paini...9200g
12 cornuri...6 paini...3600g
1) Cate paini sunt in plus?
20-6=14 (paini in plus)
2) Cate grame cantaresc cele 14 paini in plus?
9200-3600=5600 (grame in plus 14 paini)
3) Cate grame are o paine?
5600:14=400 (grame o paine)
4) Cate grame au 20 de paini?
20×400=8000 (grame 20 de paini)
5) Cat cantaresc 12 cornuri?
9200-8000=1200 (grame 12 cornuri)
6) Cate grame are 1 corn?
1200:12=100 (grame un corn)

Verificare:
3 cornuri...5 paini...2300g
3×100+5×400=300+2000=2300 g

Answer 2

Metoda comparatiei 

3 cornuri ..........5 paini .............2300 g   → o inmultesc cu 4 
4 cornuri ..........2 paini.............1 200 g   → inmultesc relatia cu 3 
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12 cornuri .......20 paini..........9 200 g  → scad relatiile 
12 cornuri .........6 paini..........3 600 g
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    /              14 paini  cantaresc = 9 200 - 3 600 = 5 600 g 

5 600 : 14 = 400 g → cantareste o paine 

Din relatia   4 cornuri ..........2 paini.............1 200 g 

1 200 g - 2 × 400 g = 1 200 - 800 g = 400 g cantaresc 4 cornuri

400 : 4 = 100 g cantareste un corn 

Verific:    4 × 100 g + 2 × 400 g = 400 g + 800 g = 1 200 g