You can adjust the scales of the axes to frame the data better, but that's more advanced that I want to get into here.

Trendline and Regression Equation

If this looks sufficiently linear, it would make sense to compute the correlation coeffcient next.

That's a fairly strong correlation so we'll move on to the regression line next. Excel calls this a "trendline". Right click on any point on the scatter plot and select Add Trendline from the menu that pops up.

The following window should appear. The Linear option should already be selected. Leave it alone. Then check both "Display Equation on chart: and "Display R-sqared value on chart".