Confidence Interval help.

#1
I have a few of these types of hw problems and can't remember the calculator function to be used.
here is an example:

The average size of a farm in Marion County is 191 acres with a standard deviation of 38 acres. The average size of a farm in Linn County is 199 acres with a standard deviation of 12 acres. The sample sizes were 8 and 10 respectively. Construct a 98% confidence interval for the true difference in means.
 
#2
We did those a few weeks ago and used the formula. Once you know the values in the formula, they are just regular math caculations on your calculator. I don't know if any function specifically for them. I could be wrong but we were not taught a calculator function and we just did these a couple of weeks ago.

Best wishes to you.