81.6∘F81.6^{\circ} \mathrm{F}81.6∘F
80.6∘F80.6^{\circ} \mathrm{F}80.6∘F
80∘F80^{\circ} \mathrm{F}80∘F
81∘F81^{\circ} \mathrm{F}81∘F