8 butelii de apa necarbogazoasa si 3 sucuri de coacaza neagra costa 127 lei,iar 4 butelii de aoa necarbogazoasa si 5 sucuri de coacaza neagra costa 137 lei.Cit costa o butelie de apa necarbogazoasa si cit costa 1 suc de coacaza neagra?
8 b + 3 s = 127 4 b + 5 s = 137, inmultim cu 2 apoi scadem cele 2 ecuatii
8 b + 3 s = 127 8 b + 10 s = 274 _______________ / 7 s = 147 s = 147 : 7 s = 21 lei 4 b + 5 * 21 = 137 4 b = 137 - 105 4 b = 32 b = 32 : 4 b = 8 lei 1 butelie de apa = 8 lei 1 suc = 21 lei
x= 1 butelie de apa y= 1 suc de coacaze 8x+3y=127 4x+5y=137 /x2 8x+3y=127 8x+10y=274 si scadem ecuatiile -7y=-147 y=21 8x+3*21=127 8x+63=127 8x=64 x=8 1 butelie de apa costa 8 lei 1 suc de coacaze costa 21 lei
