:(0.25a²b — 0.5a³b² — 1/6 a的四次方b³)÷(0.5a²b)
=0.25a²b÷(0.5a²b) — 0.5a³b²÷﹙0.5a²b) — 1/6 a的四次方b³÷(0.5a²b)
=0.5-ab-1/3a²b²