Calculate the difference between the latest quantity and the earliest quantity

[notalex]

Hey, fellow Power Bi friends 

I want to calculate the diffrence between the latest quantity and the earliest quanitity based on indexes

index	item_quantity
1	5
2	2
3	5
4	6
5	9

for example i want to know the diffrence between the item_qunaitity of the 1st index and the item_quanity of the 5th index whch is 80% ((9-5)/5)

All help will be much appreciated 

[andhiii079845]

Try this:

MeasureIndex = 
 VAR __minindex = CALCULATE(minx('Table','Table'[index])) 
 VAR __maxindex = CALCULATE(maxx('Table','Table'[index])) 
 VAR __maxindexvalue = CALCULATE(sumx(FILTER('Table','Table'[index]=__maxindex),'Table'[item_quantity ]))
 VAR __minindexvalue = CALCULATE(sumx(FILTER('Table','Table'[index]=__minindex),'Table'[item_quantity ]))
 RETURN (__maxindexvalue-__minindexvalue)/__minindexvalue