Answer:
a) 
It is changing at a rate of  units per seconds
  units per seconds
b) 
It is changing at a rate of  units per seconds
  units per seconds
Step-by-step explanation:
A
Given that:
f and g are functions of time (t):
i.e  
f(t) =0
g(t) = 0
Now; at time (t) = 2 ; f equals 5 and is rising at a rate of 6 units per second.
Also; at time 2; g equals 7 and is rising at a rate of 9 units per second
This implies that:
f(2) = 5                   f' (2) = 6
g(2) = 7                  g' (2) = 9
Then  can be directly  calculated from the  given values which is:
 can be directly  calculated from the  given values which is:

Using differentiation to determine the rate of changing ; we have
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=2}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D2%7D) 
 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=2}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D2%7D) 
 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=2}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D2%7D) =
 = 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=2}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D2%7D) 
 
∴ It is changing at a rate of  units per seconds
  units per seconds
B
Given that:
f and g are functions of time (t):
i.e  
f(t) =0
g(t) = 0
NOW; at time (t) = 3
f (3) = 9                                      f' (3) = 6
g (3) = 8                                     g' (3) = 9
Then  can be directly  calculated from the  given values which is:
 can be directly  calculated from the  given values which is:

Using differentiation to determine the rate of changing ; we have
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=3}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D3%7D) 
 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=3}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D3%7D) 
 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=3}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D3%7D) 
 
![\frac{d}{dt} [\frac{f(t)}{g(t)} ]_{t=3}](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7Bdt%7D%20%5B%5Cfrac%7Bf%28t%29%7D%7Bg%28t%29%7D%20%5D_%7Bt%3D3%7D) 
 
∴ It is changing at a rate of  units per seconds
  units per seconds
The negative signs means they are decreasing.