1/8 of the cake has not been eaten.
I can’t seem to look at the bottom two answers and the two ( A and B) are not correct. So you’re left with either C or D
The cost is the number of videos (V) times the cost of a video, plus the monthly fee.
C=2.25V+5
Let's plug the value:

Recall that exponent and logarithm are inverse operations:

So, we have
