\[(7a - 1)(a + 5) = (3 + 7a)(a + 3)\]
\[7a^{2} + 35a - a - 5 =\]
\[= 3a + 9 + 7a^{2} + 21a\]
\[7a^{2} + 34a - 5 - 24a - 9 - 7a^{2} = 0\]
\[10a = 14\]
\[a = 1,4.\]