Given data:
The total numbers of crayons are n=320.
The numbers of crayons in a packa are p=20.
The expression for the equation is,
[tex]\begin{gathered} 20x=320 \\ x=16 \end{gathered}[/tex]Thus, the expression for the equation is 20x=320 so option (C) is correct , and the numbers of pack are 16.