13.193. During exercises, a reconnaissance boat approached the lead ship of the squadron and received an order to conduct reconnaissance ahead of the squadron in the direction of its movement at a distance of 70 km. Determine how long it will take for the boat to return to the lead ship of the squadron, which continues to move forward, if it is known that the speed of the boat is 28 km/h, and the squadron must move at a speed of 14 km/h.
Solution.

Let the boat return to the lead ship after $x$ hours. In this time, the squadron will travel $14 x$ km. Therefore, the boat must travel $70+70-14 x$ km. According to the condition, $140-14 x=28 x$, from which $x=3 \frac{1}{3}$ hours.

Answer: in 3 hours 20 minutes.