Answer:
Basketball + Sports Drink
$7.50 + $2.75 = $10.25
$10.25 + ? + $13 = $30
30 - 23.25 = <u>6.75</u>
I'm pretty sure this would be because if I'm correct, the surveyors would not have known where and who they were gonna survey before they went. However, this wouldn't show accurate information because you should survey at least 100 people.
Ask google or maybe YouTube
It will be the last one since it is the one that makes more sense.