Seriously, you can't find the average of two numbers? Or is there something more complicated that I'm missing here?
Wait a minute. You say "my slope was y= 0.0165x + 0.6452". You are thinking 0.0165x + 0.6542 is the slope? That is the equation of the line. The slope is the multiplier of x, i.e. 0.0165. The other number is the intercept, which you're not interested in for present purposes.
Now, can you work out the average of 0.0165 and 0.0501?