$$ \begin{aligned} 88 &= 6k+5k&& \text{simplify right side} \\[1 em]88 &= 11k&& \text{ swap the left and right side of the equation } \\[1 em]11k &= 88&& \text{ divide both sides by $ 11 $ } \\[1 em]k &= \frac{88}{11}&& \\[1 em]k &= 8&& \\[1 em] \end{aligned} $$