1. o cutie goala - x
un creion - y
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x = 2y
x + 8y = 50
2y + 8y = 50
10y=50 , de unde y = 50/10 = 5 , deci 8y= 8 x 5 = 40
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2. pretul unei mingi - x
banii lui andrei - y
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4x=y-15
3x=y+10
scazand relatiile de mai sus se obtine
x=5
y = 3x + 10 = 3 x 5 + 10 = 15+10=25
