Ответ:

  1. \(-0.5(3x-4)+15x=4(1.5x+1)+3\).

    \(-1.5x+2+15x=6x+4+3\),
    \(13.5x+2=6x+7\),
    \(7.5x=5\),
    \(x=\frac{2}{3}\).

  2. \((2x-3)(2x+3)-x^2=12x-69+3x^2\).

    \(4x^2-9-x^2=12x-69+3x^2\),
    \(3x^2-9=3x^2+12x-69\),
    \(12x=60\),
    \(x=5\).

Ответ: а) \(x=\frac{2}{3}\); б) \(x=5\).