Solve for the missing amounts for the following separate cases.

$\backslash$table$[[$Case$,\backslash$table$[[$Sales price$],[$per unit$]],\backslash$table$[[$Variable costs$],[$per unit$]],\backslash$table$[[$Contribution$],[$margin per unit$]],\backslash$table$[[$Contribution$],[$margin ratio$]]],[1,20,16,,],[2,,30,10,],[3,,,50,20\%$