The first step is to take the logarithm of y and plot those points. If then , a straight line with slope a log(e) and y-intercept log(C). (The logarithm here is the common logarithm, base 10, since they tell you that log(e)= 0.4343)

The y value, where the line crosses the y-axis, is log(C) and so for that y value. a is the slope of that line divided by log(e)= 0.4343. If this were exactly a straight line, you could calculate the slope using any two points but with inexact measurements, it is best to use the two points farthest apart: the slope would be .