Convert the values to decimal degrees. Windows calculator can do this. It supports the coordinate format DD.MMSSsssss.
As an example, enter 0.0028125
Check on the Inv button
Click the dms button.
Or divide the seconds value by 3600.
28.125" = 0.0078125
18.75" = 0.005208333333 (unfortunately, a repeating decimal)
Melita