To find out how many miles the whale swims in 16 days, we first need to determine the whale's daily speed.
The whale swims 200 miles in 5 days, so its daily speed is:
\[ \text{Daily speed} = \frac{200 \text{ miles}}{5 \text{ days}} = 40 \text{ miles per day} \]
Now, to find out how many miles it swims in 16 days, we multiply the daily speed by the number of days:
\[ \text{Total distance in 16 days} = 40 \text{ miles/day} \times 16 \text{ days} = 640 \text{ miles} \]
Therefore, the correct equation to use is:
\[ y = 40 \times 16 \]
So the response is:
y=40×16 (y equals 40 times 16).