Ответ:x¹² · x³ = x¹⁵.a⁻³ · a⁸ = a⁵ = a⁵.t⁻⁵ · t = t⁻⁴.y⁴ · y⁻⁴ = 1.m² : m⁵ = m⁻³ = 1/m³.n⁻¹² : n⁻⁸ = n⁻⁴ = 1/n⁴.(s³)⁷ = s²¹.(x⁻⁴)⁵ = x⁻²⁰.(k⁻⁷)⁻² = k¹⁴.(x⁶y)⁻⁴ = x⁻²⁴y⁻⁴.(a⁻¹/b)⁻³ = b³/a³ = b³/a³.