Question 1183899
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18 sang and 7 sang and danced --> 11 sang but did not dance.
19 danced and 7 sang and danced --> 12 danced but did not sing.<br>
So 12 danced only; 11 sang only, and 7 did both.<br>
That makes a total of 30 who did one or the other; so 35-30=5 did neither.<br>
Conclusion:
danced: 12
sang: 11
both: 7
neither: 5<br>