Answer: $3
Step-by-step explanation:
Given
Luis has $20
He can buy 4 tennis balls and get $8 dollar back
Money spent on balls [tex]20-8=\$12[/tex]
i.e. 4 tennis balls cost [tex]\$12[/tex]
1 tennis ball costs [tex]\dfrac{12}{4}=\$3[/tex]
Each tennis ball costs $3.
