To determine the correct equation and the number of residents surveyed, we can start with the information given in the problem. We know that two-fifths of the respondents said they like spending their vacation at the beach, and that corresponds to 80 residents.
Let \( r \) be the total number of residents surveyed. According to the problem:
\[ \frac{2}{5}r = 80 \]
This equation represents that two-fifths of the total residents surveyed equals 80.
To find \( r \), we can solve for \( r \) by multiplying both sides of the equation by \( \frac{5}{2} \):
\[ r = 80 \times \frac{5}{2} \]
Calculating this results in:
\[ r = 80 \times 2.5 = 200 \]
Thus, the total number of residents surveyed is 200.
The correct equation is
\[ \frac{2}{5}r = 80 \]
and the number of residents surveyed is 200.
So the correct response is:
2/5r=80; 200 residents were surveyed.