ANSWER
6) DV
7)
8)DV
9)IV
10)DV
Step-by-step explanation
6) The quality of the goods and the price of these goods.
The quality of the goods always varies directly with the price of the goods.
7)
8) The circumference of a circle varies directly with the diameter of the circle.
9)The time elapsed for a car to cover a distance varies inversely with the speed of the car
10)The amount of interest on a principal amount varies inversely as the length of the time the principal is invested