Final answer:
In Jenny's experiment, the independent variable is the type of washing detergent used, while the dependent variable is the cleanliness of the t-shirts.
Step-by-step explanation:
In Jenny's experiment to determine if a new brand name washing detergent is better than her old detergent, the independent variable is the type of washing detergent used.
This is the variable that Jenny is manipulating and controlling. The dependent variable is the cleanliness of the t-shirts. This is the variable that Jenny is measuring to see the effect of the independent variable.