Ascientist uses different types of gasoline in the engines of three identical
cars. she measures how far the cars go before running out of gas. what is
the dependent variable in this experiment?

The distance the cars travel.

Explanation:

The independent variable is the one you change. In this case, the scientist is changing the type of gasoline used. Therefore, the type of gasoline is the independent variable.

The dependent variable is the variable that changes as a result of (or depending on) the change in the independent variable. In this case, that is the distance the car travels before running out of gas.