Log graphs

[Sal Paradise]

I have a log graph (not in excel).

I have the first X and the last X, and the corresponding Y values. I know the equation forms a straight line with a log 10 Y-axis.

Given the two X/Y pairs that I have and the nature of the line (straight in a log graph), how do I figure out the linear version of the equation? Looking at wikipedia makes me want to weep.

 

[Sal Paradise]

Solved my own problem with this handy "Finding Intercepts for Dummies" Tutorial:
http://www.humboldt.edu/~geology/courses/geology531/531_handouts/equations_of_graphs.pdf

Thank goodness for the internet sometimes.