What fraction is considered undefined?​

What's the difference between: x≥0 and nonnegative integer. ?

Type the correct answer in each box. use numerals instead of words. if necessary, use / for the fraction bar. consider the given table.

Hector and alex traded video games. alex gave hector one fourth of his video games in exchange for 6 video games. then he sold 3 video games and gave 2 video games to his brother. alex ended up with 16 video games. how many video games did alex have when he started?