3. From points $A$ and $B$, two cars set off towards each other simultaneously with constant speeds. One hour before the first car arrived at $B$ and four hours before the second car arrived at $A$, they met. Find the ratio of the speeds of the cars.
3. Answer: the speed of the first car is twice as high.

Let the speed of one car be $k$ times the speed of the other. Since they started at the same time, one car will travel a distance $k$ times greater. After this, the segments will switch, and the slower car, whose speed is $k$ times less, will have to cover a distance $k$ times greater. It is clear that it will take $k^{2}$ times more time for this. In our case, this number is 4, from which $k=2$. That is, the speed of the first car (which has less time left to travel) is twice the speed of the second.