I believe it would just be -1
The answers are:
1) 
2) 
3) 
The explanation for this answer is shown below.
1. To solve this problem you must apply the following proccedure:
2. You have the function 
3. You must switch
and
and then solve for
:

4. Finally, you obtain:

The solution for b could really be any answers as long as when that number is divided by 4.3 it is less than 11.3
1 possible answer though could be 11.3
Because when 11.3 is divided by 4.3 it is less then 11.3
Sorry if I'm missing something and the answer is wrong!