Give examples of directly proportional quantities.

Two quantities are called directly proportional if the following condition is met:
with an increase (decrease) in one of the quantities x times, the second quantity also increases (decreases) x times.
Now let us find the quantities satisfying this condition.
For example, with a constant width, the length of the rectangle and its area are directly proportional. If you increase the length x times, then the area will also increase x times, since it is equal to the product of the length and width of the rectangle.
The speed of the body and the distance traveled by it are also directly proportional (provided that time is unchanged).