ISDS 3115 Homework Help Needed

trying to get as much as I can done before the game starts.

Here's the question: Find the simple linear regression equation that shows the relationship between number of patients and year is

Y= ___ + ____x

you're given:

years 1 2 3 4 5 6 7 8 9 10
Number of patients: 36, 32, 39, 42, 42, 56, 58, 53, 57, 61
Robbery Rate: 58.0, 61.4, 73.4, 75.7, 78.5, 88.6, 101.1, 94.8, 104.1, 115.6

I know the slope equation is sum of xy-n(average of xy) divided by the sum of x^2 - n(average of x)^2

But when I plug in my numbers I always get the wrong answer.

The Help Me Solve This uses 7 for n even though there is 10 years which is weird to me. BTW, the average of xy and x is shown as a x with a bar over it. Just so you know what Im talking about. So can anyone help me out here? I need to understand how to get to the right answer.