Final answer:
To find the percent of tennis balls out of the total number of balls, divide the number of tennis balls by the total number of balls and then multiply by 100.
Step-by-step explanation:
To find the percent of tennis balls out of the total number of balls, divide the number of tennis balls by the total number of balls and then multiply by 100.
In this case, Archie has 39 tennis balls out of 100 total balls. So, the fraction of tennis balls is 39/100. Multiplying this fraction by 100 gives a percent of 39%.