No point on Earth can have both an east and a west coordinate. Since you called
the first number a "latitude", it must be a north or south latitude.
If you meant to say 15 North / 12 west, the point is located in the Pacific Ocean,
about 1,345 miles due south of Goleta, California, and about 1,820 miles due west
of the coast of Mexico.
If you meant to say 15 South / 120 west, that point is also in the Pacific Ocean,
about 3,420 miles south of Goleta, and 2,970 miles due west of the coast of Peru.
The country located at 31 degrees North latitude and 123 degrees East longitude is China.
The country located at 15 degrees latitude east of Vietnam is Laos.
The country located at 50 degrees north latitude and 4 degrees east longitude is Belgium.
Antarctica is located 0 degrees north and 40 degrees east.
The coordinates 36 degrees north latitude and 138 degrees east longitude point to Japan.
About 20 degrees east latitude to 40 degrees east latitude.
The country located at 31 degrees North latitude and 123 degrees East longitude is China.
The country located at 15 degrees latitude east of Vietnam is Laos.
The country located at 50 degrees north latitude and 4 degrees east longitude is Belgium.
It is on the country of Gabon
Antarctica is located 0 degrees north and 40 degrees east.
The coordinates 36 degrees north latitude and 138 degrees east longitude point to Japan.
Since California is located in USA, the nearest country east of USA and at 40 degrees north latitude is Portugal.
Finland is located at 70 degrees north latitude and 28 degrees east longitude.
Finland
Chad
Kenya.