a) The first new moon was on the 24th day
b) The second new moon was on the 51 st day
c) There are approximately 27 days between the two new moons
Firstly, we want to get the first new moon
The first new moon corresponds to 0% visibility
We trace the point at which we have the first intercept on the x-axis
We can see that the first intercept was on the 24 th day
Secondly, we want to get the day for the second new moon. This is the second intercept on the x-axis
We have this on the 51 st day
Thirdly, we want to get the number of days between the new moons
We simply make a subtraction of the first new moon from the second
That would be 51-24 = 27 days