To find the number of residents surveyed, we can start with the information provided: two-fifths of the respondents (denoted as \( r \)) equals 80 residents who like spending their vacation at the beach.
We can set up the equation as follows:
\[ \frac{2}{5} r = 80 \]
To solve for \( r \), we can multiply both sides of the equation by \( \frac{5}{2} \):
\[ r = 80 \times \frac{5}{2} = 80 \times 2.5 = 200 \]
Thus, the number of residents surveyed is 200.
The equation that represents the number of residents surveyed is:
\[ \frac{2}{5} r = 80 \]
So the correct option is:
Start Fraction 2 over 5 End Fraction r equals 80 ; 200 residents were surveyed.