Vector Algebra

Let $\bar{a}$ and $\bar{b}$ be two vectors such that $|\overline{\mathrm{a}}|=1,|\overline{\mathrm{~b}}|=4, \overline{\mathrm{a}} \cdot \overline{\mathrm{b}}=2$. If $\overline{\mathrm{c}}=(2 \overline{\mathrm{a}} \times \overline{\mathrm{b}})-3 \overline{\mathrm{~b}}$, then the angle between $\overline{\mathrm{b}}$ and $\overline{\mathrm{c}}$ is