Odpowiedź:
[tex]\left\{ \begin{array}{l} x + y = 58 \\ x + 2z = 60 \\ x + y + z = 75 \end{array}[/tex]
x + y = 58
y = 58 - x
x + 2z = 60
2z = 60 - x
z = 30 - 0,5x
x + y + z = 75
x + 58 - x + 30 - 0,5x = 75
-0,5x = - 13
x = 26
x + y = 58
26 + y = 58
y = 32
x + 2z = 60
26 + 2z = 60
2z = 34
z = 17
[tex]\left\{ \begin{array}{l} x = 26 \\ y = 32 \\ z = 17 \end{array}[/tex]