[tex]0.5(6 + x) = 2.5(x + 4) \\ 3 + 0.5x = 2.5x + 10 \\ 2.5x - 0.5x = 3 - 10 \\ 2x = - 7 \\ x = - \frac{7}{2} \\ x = - 3 \frac{1}{2} \\ x = - 3.5[/tex]