If f(x)=69-15x then 
Given :

Lets find out
. The steps to find out f inverse are
Replace f(x) by y

Now we find 
Replace inverse function in the place of x in f(x)

Learn more :
brainly.com/question/11242094
Answer:
x=10
Step-by-step explanation:
18x=180
x=10
if my answer helps please mark as brainliest.
The equation which models the distance (d) of the weight from its equilibrium after time (t) is equal to d = -9cos(2π/3)t.
<h3>What is the period of a cosine function?</h3>
The period of a cosine function simply means the total length (distance) of the interval of values on the x-axis over which a graph lies and it's repeated.
Since the weight attached is at its lowest point at time (t = 0), therefore, the amplitude of equation will be negative nine (-9)
For the angular velocity at time period (t = 3s), we have:
ω = 2π/T
ω = 2π/3
Mathematically, the standard equation of a cosine function is given by:
y = Acos(ω)t
Substituting the given parameters into the formula, we have;
d = -9cos(2π/3)t.
Read more on cosine function here: brainly.com/question/4599903