I must "extract" the negative value from the received HEX strings.

Example:

Latitude = 10D27FBC (HEX)

= 282230716

Actual Latitude is 28.2230716

This is correct as it is a positive value.

Longitude = F0B00A5E (HEX)

= 4038068830

This should be -25.6898466

How do I determine whether the HEX value is negative - then convert the decimal value?