Vector Algebra

If \(\left( {\overrightarrow a + 3\overrightarrow b } \right)\) is perpendicular to \(\left( {7\overrightarrow a - 5\overrightarrow b } \right)\) and \(\left( {\overrightarrow a - 4\overrightarrow b } \right)\) is perpendicular to \(\left( {7\overrightarrow a - 2\overrightarrow b } \right)\), then the angle between \(\overrightarrow a\) and \(\overrightarrow b\) (in degrees) is _______________.