First let's find the total amount of free time he has in 7 days or one week.
5 * 7 = 35 hours of free time
Now we need to add the 8 hours for video games to the 13 hours of internet
8 + 13 = 21
To find the percent we can use this formula
21/35 = x/100 we can simplify 21/35 to 3/5 so it would be
3/5 = x/100 We cross multiply to get 5x = 300
x = 60
60% of his free time is spent on the internet and playing video games.