I have not done question 9 yet. Maybe you should give it a try first and see where you get stuck
Differential equations mostly test separation of variables and thus involve in log form. (shift the functions/variables to the left and leaving the constant to the right)
I. E. dx/dt=k(1-x)
1/1-x dx/dt= k
Hence by integrating with wrt to t, you can "see" that dx/dt would become dx and the right side become dt. Then inte as per normal.
At least this is how I remember.

Also, don't shift the variables for which it can be integrated to.
IE. dx/dt=kt(1-x)
1/1-x dx/dt=kt
Inte wrt to t