b⁻¹⁰ ⋅ (5b⁴)³ = b⁻¹⁰ ⋅ 5³ ⋅ (b⁴)³ = 125 ⋅ b⁻¹⁰ ⋅ b¹² = 125 ⋅ b².
При b = -0,8, имеем: 125 ⋅ (-0,8)² = 125 ⋅ 0,64 = 80.