How speed, distance and time relate to each other is always the same. The values might change but the relationship doesn't.
An easy way to remember these relationships (or formulae) is to put distance, speed and time (or the letters D, S and T) into a triangle.
The triangles will help you remember these three rules:
On the next page there are some examples to work through.
Have paper and a pen handy, draw the distance, speed and time triangle on your paper, then try the examples.