I have this knapsack problem
\begin{align} \max {z}=10&x_1+8x_2-13x_3 +10x_4+10x_5 + 5x_6\\[0.4cm] \text{s.t. }\quad\,\,\,7&x_1+6x_2+10x_3+\,\,\,8x_4 +\,\,\,9x_5 + 5x_6\le39 \\[0.2cm]& x_i\ge0 \end{align}
and I want to solve it using duality. I have converted it to dual but I don't know what to do next. The (D) is:
\begin{cases} \text{min }w=&39y\\ &7y \ge 10\\ &6y \ge 8\\ &10y \ge 13\\ &8y \ge 10\\ &9y \ge 10\\ &5y \ge 5\\ \end{cases}