Odpowiedź:
[tex]a) \: x + 15 = 23 \\ x = 23 - 15 \\ x = 8[/tex]
[tex]b) \: 3x = 21 \\ x = 21 \div 3 \\ x = 7[/tex]
[tex]c) \: 2x - 5 = 11 \\ 2x = 11 + 5 \\ 2x = 16 \\ x = 16 \div 2 \\ x = 8[/tex]
[tex]d) \: - 3x + 4 = x + 8 \\ - 3x - x = 8 - 4 \\ - 4x = 4 \\ x = 4 \div ( - 4) \\ x = - 1[/tex]
