\[(8x - 1)(8x + 1) - (16x - 3)(4x + 1) =\]
\[= 64x^{2} - 1 - 64x^{2} + 12x - 16x + 3 =\]
\[= - 4x + 2;\]
\[x = 0,3:\]
\[- 4 \cdot 0,3 + 2 = - 1,2 + 2 = 0,8.\]