If that is 6-3(log2n)=0 then how you would go about solving it is by looking at log2n like x. In this case, for 6-3x=0, x would have to =2. So log2n has to =2. If log2n=2 and we assume that the base is 10 (because if there is no written base on a log then it is 10) then we need to rewrite the log to exponential form. Rewritten it's 10^2=2n. 100=2n, divide both sides by 2 and you get n=50.
Answer:
The pink angle is half the angle subtended by the blue arc.
Step-by-step explanation:
Given
See attachment for circle
Required
Compare the pink angle to the blue arc
Let the pink angle be x and the angle subtended by the blue arc be y.
So, we have:
angle at circumference
angle subtended by arc
The relationship between x and y is:

Make x the subject

Add 165 to 245. That is a total of 410kWh.
245kWh is more than 50% of 410kWh.
So, according to the plan, you will pay NightTimer rate for kWh at night and DayTimer rate during the day.
The work done:

The raw, accurate, answer is that the value to pay is $22.08085.
In real terms, it is closer to your $22.08 option. That is the one I'd take.