a)
[tex]x + 9 = 15[/tex]
[tex]x = 15 - 9 = 6[/tex]
b)
[tex]2 \times x + 8 = 5 + x[/tex]
[tex]2x + 8 = 5 + x[/tex]
[tex]2x - x = 5 - 8[/tex]
[tex]x = - 3[/tex]
c)
[tex]6 \times x - 2 = 8 \times x + 12[/tex]
[tex]6x - 2 = 8x + 12[/tex]
[tex]6x - 8x = 12 + 2[/tex]
[tex] - 2x = 14[/tex]
[tex]x = 14 \div ( - 2) = - 7[/tex]
d)
[tex]2 \times x - 8 - 5 \times x + 6 = 5 + 4 \times x + 7[/tex]
[tex]2x - 8 - 5x + 6 = 5 + 4x + 7[/tex]
[tex]2x - 5x - 4x = 5 + 7 + 8 - 6[/tex]
[tex] - 7x = 14[/tex]
[tex]x = 14 \div ( - 7) = - 2[/tex]
