To identify an equation to find out how many miles the whale swims in 16 days, we first need to determine the average distance it swims per day.
The whale swims 200 miles in 5 days, so we can calculate the average distance per day as follows:
\[ \text{Average miles per day} = \frac{200 \text{ miles}}{5 \text{ days}} = 40 \text{ miles/day} \]
Now, to find the total distance (D) the whale swims in 16 days, we can use the equation:
\[ D = \text{Average miles per day} \times \text{Number of days} \]
Substituting the values we have:
\[ D = 40 \text{ miles/day} \times 16 \text{ days} \]
So the equation you can use to find how many miles the whale swims in 16 days is:
\[ D = 40 \times t \]
where \( t \) is the number of days (in this case, 16). By substituting \( t = 16 \):
\[ D = 40 \times 16 = 640 \text{ miles} \]
Thus, the whale swims 640 miles in 16 days.