Longitudes cannot be N or S so it must be 30 E.
They're labeled E (or W) to show that they're (E)ast or (W)est of the prime meridian (which is the line of longitude passing through Greenwich Observatory near London). 15 degrees East and 15 degrees West are the same distance from the prime meridian, but in opposite directions.
20! = 2.432902008176 E+18
According to Google Maps, 15N 60E is in the Arabian Sea
The volume of sphere = (4/3)*pi*r3 where r is the radius. The diameter of a ping pong ball is 40 mm or 1.5478 in. the radius is 20 mm. r3 is 8000 mm3 The volume is 33510 mm3 or or 33.51 cc or 2.045 in3
Indian Ocean
Latitude: 10°20′S to 27°SLongitude: 30°10′E to 40°10′E
Greece
Latitude: S 4° 40' 46.4664" | Longitude: E 55° 29' 31.1172"
That point is on the Indian subcontinent, a part of Asia, about 220 miles northwest of Bangalore.
Greece
No, neither of those does.
Longitude of Belgrade: 20°27′44″E
40 degrees North intersects with 20 degrees East in Albania. It is about 20 miles from the Albanian border with Greece.
Approximate latitude: 28°30′N to 37°25′N Approximate longitude: 38°40′E to 48°40′E
Africa
Latitude: N 40° 8' 35.178" / Longitude: E 47° 34' 36.9372"