(-5/-6)×а×(-4/-5)×в×(3/8)

(-5/-6) * а *  (-4/-5)*b *(3/8) == ( ⁵/₆  *  ⁴/₅  * ³/₈) *ab == (  ⁵*⁴*³ / ₆*₅*₈ ) *ab == ( ¹*¹*¹/  ₂* ₁*₂ ) ab == ¹/₄ * ab  = 0.25ab