formula help

Hi there i am trying to calculate a formula in excel for a fuel test survey i need to use data validation to create a drop down for column J using values from k and l then column m using values from i and j
The purpose is that litres will be calculated automatically and mpg as well ?

letmein said:

The purpose is that litres will be calculated automatically and mpg as well ?

Click to expand...

You are unclear?
You should enter a few rows of expected results.
If I understood you well, see if you help attached example.

navic said:

You are unclear?
You should enter a few rows of expected results.
If I understood you well, see if you help attached example.

Click to expand...

OK I have uploaded again the three fields i have highlight in red i want them to be in a drop down fromula as when a user presses delete the =h2-g2 formula will remove and have to be entered again i tried to enter my formula in data calabiration using custom field but that did not work View attachment Fuel_Test_v1.xlsx

I'm sorry I can not understand you well. I can not help you
Good luck