Output wood steel Igor 6 9 Johnny 18 3 What is Igor's opportunity cost for 6 units of wood? 1 units of (select unit) What is Igor's opportunity cost for 1 unit of wood? units of (select unit) What is Johnny's opportunity cost for 18 units of wood? units of (select unit) What is Johnny's opportunity cost for 1 unit of wood? units of (select unit) What is Igor's opportunity cost for 9 units of steel? units of (select unit) What is Igor's opportunity cost for 1 unit of steel? units of (select unit) What is Johnny's opportunity cost for 3 units of steel? units of (select unit) What is Johnny's opportunity cost for 1 unit of steel? units of (select unit)