Help needed for formula

[jiji]

I have a database with several variables, such as below:

Sys. Diameter; Dia. Diameter; Pressure; Distentibility

There are several numbers under sys. diameter, dia. diameter, and pressure.

What I want to do is calculate distensibility, using the formula (2*((Sys.Diameter - Dia.Diameter)/Dia.Diameter))/Pressure

Is there a way to calculate distensibility automatically for each row without having to plug in the numbers into a formula each time?

Thanks

[NBVC]

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