A zero in front of the x would make this a difference of two perfect squares. All of the other option would interfere by adding another term.
Take into account, that in general, a cosine function of amplitude A, period T and vertical translation b, can be written as follow:

In the given case, you have:
A = 4
T = 3π/4
b = -3
By replacing you obtain:

Hence, the answer is:
f(x) = 4cos(8/3 x) - 3
So if it is 60 miles per hour it is basically 60 miles per 60 minutes.
when you simplify it, it is going to be 1/1=1 The answer is 1 mile per minute
Total owed to the business = $100,000
amount that could not be collected = $5000
Fraction of total not collected
20,000 Hz = 2 × 10^4 Hz
150,000 Hz = 1.5 × 10^5 Hz