A café in Shillong noted which drinks its regulars like. How many like exactly one of tea and coffee (whether or not they like juice)?

Tea but not coffee $=16+5=21$ and coffee but not tea $=21+9=30$, so exactly one of the two $=21+30=51$. 37 forgets the parts that also like juice, 58 wrongly adds the 7 who like both, and 54 wrongly adds the 3 in the centre.