

Ich bin zwanzig Jahre alt.
[ˈɪç ˈbɪn ˈtsvantsɪç ˈjaːrə ˈalt.]
I'm twenty years old.
Das kostet zwanzig Euro.
[das ˈkɔstət ˈtsvantsɪç ˈɔɪ̯ro.]
That costs twenty euros.
Hast du zwanzig Minuten Zeit?
[ˈhast ˈduː ˈtsvantsɪç miˈnuːtn̩ ˈtsaɪ̯t?]
Do you have twenty minutes?
"zwanzig" is in the lesson "Big numbers" (Level 4), along with 11 other useful words. LinDuo has 180 topic lessons like this one, 2,375 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.