If you would like to know if a stand will support a 21-kg television, you can find this using the following steps:
1 kilogram = 2.20462262 pounds
1 kilogram = 2.2 pounds
21 kilogram = 21 * 1 kilogram = 21 * 2.2 pounds = 46.2 pounds
46.2 pounds > 40 pounds
The correct result would be: No, the stand won't support a television.