The answer you're looking for is 40 tennis balls.
Hope this helped!
Answer:

<em><u>I </u></em><em><u>hope </u></em><em><u>it </u></em><em><u>helps</u></em>
<em><u>have </u></em><em><u>a </u></em><em><u>great </u></em><em><u>day </u></em>
<em><u>
</u></em>
I think the answer is that what i think