Answer:
The solution is 1.
Step-by-step explanation:
Logarithm:
Suppose we have a logarithmic equation in the following format:

It means that:

In this question:

Which means that:

Every number, elevated to 0, is 1. So

Which means that the solution is 
Answer
67.5
45° would be the other angle of 2x°
180° - 45° = 135°
135/45 = 67.5°
That is 5*20 is 100 and the inverse of 5 is 25
B) because the rate of change is 7, while for A the rate of change is 6 and for C and D the rate of change is 4