How to calculated hours from attribute in3

The device is not report attribute "ignition" then the total hours is not calculated. Can we use for "in3" (true/false) attribute to calculate hours instead?

positions[0].attributes
{
    "in3": true,
    ...
}

If you have an example that would be great.
Thank you.

Try:

Attribute: ignition
Expression: in3?true:false
Type: boolean

thank you. it worked.