What percent of city residents have Facebook or Instagram accounts? What percent of city residents have neither a Facebook nor an Instagram account?

Question

A survey of a city’s residents shows that 62% have a Facebook account, 78% have an Instagram account, and 56% have a Facebook and an Instagram account

Answer 1

Based on the information, it might be useful to build a little Venn Diagram of the situation.

If there are 56 that have both and 62 that have FB, then 6 have only FB (no IG).

If there are 56 that have both and 78 that have IG, then 22 have only IG (no FB).

That means the total that have either FB or IG is 6 + 56 + 22 = 84. Since there are 100 total, then 16% have neither.