∠ACM=∠BCN=60°
∠ACN=∠BCM
AC=CM,CB=CN
△ACN≌△MCB
∠NAC=∠CMB
∠BFA=∠MAF+∠AMF =∠MAF +∠AMC +∠CMB =∠AMC +∠MAC =120°
∠NFB=180°-120°=60°