The stretch of a spring in milliliters is proportional to the weight in grams attached to the end of the spring find the unitary
unit of proportionality for this relationship.
The unitary unit of proportionality for this relationship can be found by dividing the unit of the dependent variable (stretch in milliliters) by the unit of the independent variable (weight in grams). In this case, it would be milliliters per gram (mL/g).
So, the unitary unit of proportionality for this relationship is mL/g.