[tex]y + 9 = 9 | - 9 \\ y+ 9 - 9 = 9 - 9 \\ y = 0[/tex]
[tex]10 + 2x = 20 | - 10 \\ 10 + 2x - 10 = 20 - 10 \\ 2x = 10 | \div 2 \\ 2x \div 2 = 10 \div 2 \\ x = 5[/tex]
[tex]17 + 3c = 26 | - 17 \\ 17 + 3c - 17 = 26 - 17 \\ 3c = 9 | \div 3 \\ 3c \div 3 = 9 \div 3 \\ c = 3[/tex]
[tex]x - 4 = 3 | + 4 \\ x - 4 + 4 = 3 + 4 \\ x = 7[/tex]
[tex]2z - 7 = 7 | + 7 \\ 2z - 7 + 7 = 7 + 7 \\ 2z = 14 | \div 2 \\ 2z \div 2 = 14 \div 2 \\ z = 7[/tex]
