You will first have to change your text file so that ArcMap can understand it by adding a header:
![](/legacyfs/online/401517_pastedImage_1.png)
The add it to ArcMap, which will interpret it as a table:
![](/legacyfs/online/401518_pastedImage_3.png)
Use the Add XY events option to create point features with the appropriate coordinate system:
![](/legacyfs/online/401534_pastedImage_4.png)
Followed by selecting the right fields:
![](/legacyfs/online/401535_pastedImage_5.png)
and define the coordinate system (not sure if this the correct one in my screenshot below)
![](/legacyfs/online/401536_pastedImage_6.png)
When you have the point events you can use the project tool to create a physical output featureclass with the WGS 1984 geographic coordinates:
![](/legacyfs/online/401537_pastedImage_7.png)
and add coordinates:
![](/legacyfs/online/401538_pastedImage_8.png)
to obtain the decimal degrees of the geographic coordinates as attributes in the featureclass:
![](/legacyfs/online/401539_pastedImage_9.png)