Question

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?

Answer 1

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

Answer 2

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