creating line charts with trendlines

[deSanta]

I want to create a line chart based on a data similar to the one below. need to have 'CLASS' in the x axis, and 'SCORE' in the y-axis. Then I need to add a trendline, and have a slicer for 'ID' .  Finnaly I need to have a card that shows the slope of the trendline. 

ID	CLASS	SCORE
1	a	-2
2	a	1
3	a	6
1	b	4
2	b	3
3	b	-5
1	c	-2
2	c	4
3	c	6
1	d	-1
2	d	3
3	d	7

I am new at power BI, so I am not well versed in writting DAX. I noticed that power BI only shows the trendline option in the Analytics tab when both x and y axis are numerical. Also, I could not find an option to display the slope of the trendline even if I convert my categorical column into numerical. I tried to follow a previously posted example  to manually create the  trendlines, but the slope of the trendline I obtained never changes when a new ID is selected in the slicer.

I would sincerelly appreciate the help.  

[amitchandak]

@deSanta , That option is only available with Date/Numbers on the x-axis