Microsoft Excel allows you to graph your data into a chart. Then using the chart, Excel can put in a trend line. The trend line is also known as the leastsquares regression line. This line has a formula, y=mx+b. B is the yintercept. M is the slope. X is the point on the xaxis where the spot is and y is the point on the y axis where the spot is. Excel will graph and define your line's equation for you, so the slope is the m in y=mx+b. For example, if the line's equation is y=2*5+4, then the slope is 2.

Graph your data using whichever type of graph you find appropriate. Each data set is different, but most likely, you will use a line graph that plots the points on the graph.

Click on your graph in Excel.

Click the "Layout" tab, then click "Trendline." Select the "Linear" trend line.

Click "More Trendline Options." Check the box next to "Display Equation on chart."

Find the slope in the equation. The equation is formatted as y=mx+b. The slope is the number in the m spot.