

Брату уже семнадцать лет.
My brother is already seventeen years old.
Встречаемся в семнадцать часов.
We're meeting at 17:00.
Это не семнадцать, а семьдесят.
That's not seventeen, it's seventy.
"семнадцать" is in the lesson "Numbers" (Level 3), along with 19 other useful words. LinDuo has 180 topic lessons like this one, 2,380 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.