In a survey of 80 youths on phone preferences, 10 liked neither iPhone nor Android. If the ratio of youths who liked iPhone only to Android only is 3:2, and 10 liked both, how many liked each type of

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1. Survey of Youths
Let I be the set of youths who liked iPhone and A be the set of youths who liked Android.
Total youths surveyed = 80.
Number of youths who liked other types of phones = 10.
Number of youths who liked both iPhone and Android, n(I $\cap$ A) = 10.
Number of youths who liked iPhone or Android or both, n(I $\cup$ A) = Total youths - Youths who liked other types = $80 - 10 = 70$.
The ratio of the number of youths who liked iPhone only to the number of youths who liked Android only is 3:2.
Let n(I