I need to calculate the total hours on a Works order form I have - but I am unsure how to fetch the data. The app work's like this:

A form called Machines has the run time of each item identified by the Drawings form. This is linked with a field called Drawings_no

There is another form called Works order which the user selects the from  drawing_no field and enters a quantity then I need Zoho to do a small calculation of the quantity the user entered times the run_time stored on the Machines form. (the run_time is how many minutes it takes to make 1 part)

I hope this makes some sense. My app is open for employee access if it is easier for you to have a look at it yourself.

Thank you in advance - if you need any more information please ask.

Many thanks

Ben