Some boats have motors and go further into the sea. Since they go far out they can catch more fish. These boats travel faster, at a speed of about $20 \mathrm{km}$ in one hour. How much time will they take to go $80 \mathrm{km}?$

Given:
The speed of the boat in one hour = $20 \mathrm{km}$
To find:
The time taken to travel $80 \mathrm{Km}$
Solution:

From the given,

The speed of the boat is $20 \mathrm{km}$ per hour.

Using the distance-time formula:

$$\begin{gathered} Speed=\frac{Dis\tan ce}{Time taken} \\ \Rightarrow Time=\frac{Dis\tan ce}{Speed} \end{gathered}$$

Finding the time taken by the boat to cover  $80 \mathrm{Km}$ at a speed of $20 \mathrm{km}$ per hour,

$$\begin{gathered} Time =\frac{80}{20} \\ =4 hours \end{gathered}$$

Thus, it takes $4$ hours for the boat to cover a distance of $80 \mathrm{Km}$.

Hence, option A is correct.