Answer
P(35 to 44 years of age or uses social media) $=\frac{187}{265}\approx0.706$
Work Step by Step
The sample space: 530 adult Americans. So, N(S) = 530.
According to the marginal distribution (see definition, page 235) of the first row: N(uses social media) = 338.
According to the marginal distribution (see definition, page 235) of the second column: N(35 to 44 years of age) = 125
According to the cell in the first row, second column: N(35 to 44 years of age and uses social media) = 89.
P(35 to 44 years of age or uses social media) =
P(35 to 44 years of age) + P(35 to 44 years of age) - P(35 to 44 years of age and uses social media) =
$\frac{N(\text{35 to 44 years of age})}{N(S)}+\frac{N(\text{uses social media})}{N(S)}-\frac{N(\text{35 to 44 years of age and uses social media})}{N(S)}=\frac{125}{530}+\frac{338}{530}-\frac{89}{530}=\frac{374}{530}=\frac{187}{265}\approx0.706$
