If you're betting one coin per draw, then in 80 draws you risk 80 coins. On each of the 20 on which your number is drawn, you get three coins back. So at the end of an average 80 draws, you have ...

There's no strategy to win. The player picks a series of numbers from 1 to 80, and if the numbers are among the 20 drawn by a random number generator at lottery headquarters, the player might win.