How do we know if a graph represents either direct or inverse proportionality? We look for certain features of the graph and perform some test calculations to help us decide. Look at this graph: The ...

There is a direct proportion between two values when one is a multiple of the other. For example, \(1\text{cm} = 10\text{mm}.\) To convert \(\text{cm}\) to \(\text{mm}\), the multiplier is always 10.