Given data:
The given cost of 3 cookies is 10.50.
a)
The cost of one box of cookies is,
[tex]\begin{gathered} 3\text{cookies}=10.5 \\ 1\text{ cookie=3.5} \end{gathered}[/tex]Multiply 7 on both sides.
[tex]\begin{gathered} 7\text{ cookies=7(3.5)} \\ 7\text{ cookies =24.5} \end{gathered}[/tex]b)
The cost of n boxes of cookies is,
[tex]c=3.5n[/tex]Thus, the cost of n boxes is 3.5n.
