T = k/R where k is the constant of variation, T=time and R=speed.
Plug in the given values:-
12 = k/60
k = 12*60 = 720
So the equation of variation is T = 720/R
At 85 mph we have
T = 720 / 85 = 8.47 hours (answer)
We can do this easily using 0s.
(x - i) (x + i) (x + 4) (x - 1) = 0
If you plug in any of the numbers, you'll get 0, making the equation true.
we have

Group terms that contain the same variable, and move the constant to the opposite side of the equation

Combine like terms

Divide by
both sides


therefore
<u>the answer is</u>
the value of p in the linear equation is 
The rule of a geometric sequence:

We have:

Find 
substitute:
