Let a be temperature A and b be temperature B.

The equation of a line is "y = mx + b." If we call "b" the y variable and "a" the x variable, we have that the form for a line is

<-- I needed to change the "b" for the y-intercept.

So try this:

Picking the first two in the set gives:

Pick any point on the (alleged) line:

You can verify that the equation b = -3a + 80 gives the relationship between a and b.

Obviously this will only work if there is, in fact, a linear relationship between the two data sets...

-Dan