Answer
17.6ft/s
Work Step by Step
First lets covert the fox's speed in ft/s. The fox runs at a speed of 42mi/h. The question tells us that there are 5280 ft in one mile so we can multiply the numerator in miles by 5280 in order to get it in ft.
42mi $\times$ 5280 = 221,760 ft.
Now, our speed is 221,760 ft/hour. We need to convert the bottom denominator in hours to seconds. We know that there are 3600 seconds in 1 hour so we can multiply 3600 by the denominator to get our speed in ft/s. The denominator is 1 so we can just put 3600 in the denominator. Our speed now is,
$\frac{221,760 ft}{3600s}$
Simplify this fraction by dividing it by the denominator, 3600. We get:
$\frac{61.6ft}{s}$
So now in order to find the difference we subtract the two speeds from each other. The speed of the car is 44ft/s, so:
61.6ft/s - 44ft/s = 17.6ft/s
So our difference is 17.6ft/s.