As Wikipedia says:

The t-test is any statistical hypothesis test in which the test statistic follows a Student's t-distribution under the null hypothesis. (Emphasis added.)

The equation you link to:

is only for the case of a one-sample t-test when you are comparing the mean of a set of observations against a specified value .

Your Excel model is a linear regression of price against area, so that formula isn't what you need. The t statistic that you highlighted in the Excel report is for the slope of the regression line. Several ways to do the calculations for that application of a t-test are provided here.

1. Having 21 at the start of both sets of data led to some confusion about which points were being compared with which; a different example (or explicitly identifying both sets in the diagram, not just the second one) could avoid that ambiguity.

2. Note that if these are time series data, the assumption of independence will usually not be tenable.

3. You don't need a macro, Excel has a built in t-test function (T.TEST) that is capable of doing what you ask for.

   T.TEST(array1,array2,tails,type)

   array1 and array2 should be two non-overlapping sets of observations.

   tails should be 1 or 2 depending on whether you need a 1- or 2-tailed test. I presume you want two tailed. (If it's one-tailed, beware; it actually just reports half the two-tailed p-value, which is not correct if the sample means are in the opposite direction to the one hypothesized in the one-tailed alternative.)

   type is 1,2 or 3 depending on whether you want paired, independent with equal variance or independent with unequal variance. (It's possible to make the paired test option do a one-sample t-test as well)

   There's an explicit example of using this function at the link above.

4. With your approach you next need to compute the t-statistic before trying to use the t.dist function; that's the first argument.