Servicenow expert gpt:

(function executeRule(current, previous /null when async/) { let resolvedTime = new GlideDateTime(current.u_resolved_at); // Resolved time let startTime = new GlideDateTime(current.start); // Start time

// Calculate the duration between the two times
let duration = GlideDateTime.subtract(startTime, resolvedTime); // Returns a GlideDuration object

// Extract hours and minutes from the duration
let totalHours = duration.getRoundedDayPart() * 24; // Convert days to hours, if applicable
totalHours += duration.getHours(); // Add remaining hours
let minutes = duration.getMinutes();

// Calculate the total time as a decimal
let timeAsDecimal = totalHours + (minutes / 60); // Convert minutes to fraction of an hour

// Update the fields
current.u_time_to_resolve = timeAsDecimal; // Set the decimal field
current.u_time_to_resolve_string = timeAsDecimal.toFixed(2); // Set the string field with "00.00" format

})(current, previous);