Answer: C)The yellow car was faster. Yellow traveled at a speed of 50 mph while green was traveling at an average of 40 mph.
Step-by-step explanation:
The speed of each car is defined as:
![v=(d)/(t)](https://img.qammunity.org/2019/formulas/physics/middle-school/4gu7lgqv4de43cmjgdyd21vu6ajahiims6.png)
where d is the distance traveled by the car and t is the time taken.
For the yellow car, d=400 mi and t=8 h, so its speed is
![v=(400 mi)/(8 h)=50 mph](https://img.qammunity.org/2019/formulas/physics/middle-school/k7o646q0l8xj2kk9cmf1kmc97ohap9k3bi.png)
For the green car, d=400 mi and t=10 h, so its speed is
![v=(400 mi)/(10 h)=40 mph](https://img.qammunity.org/2019/formulas/physics/middle-school/2tme7xfkbfaa1p5tks8ehvabd0tqsr7o10.png)
So, the correct choice is
C)The yellow car was faster. Yellow traveled at a speed of 50 mph while green was traveling at an average of 40 mph.