Forecast Consumption Chart

[Alphix]

Hi I am trying to track paint consumption. I have 50 gallon drums in which a machine consumes at different
rates until empty. I log down the gallons used per day.

I have 2 to 4 drums on hand at time.

I need to chart this information and have the chart forecast on when the 4 drums will be done on what day.
Please help.

Thank you.