Как по Английски будет третий десяток

cardinal number

The number equivalent to the product of two and ten; ten less than thirty; 20.

Примеры использования:

Twenty or thirty years ago

plural noun

The numbers 20 through 29

Примеры использования:

Temperatures were in the twenties (= between 20° and 29°)., both of our children are now in their t…