Danica is arranging flowers for a party. On each table, t, there will be a vase of 9 flowers and 3 bowls of flowers with f flowers inside. Danica needs an additional 12 flowers for a cake topper. This situation can be written as the following expression: 9t + (3f)t + 12 How many flowers should Danica purchase if she has 21 tables with 3 flowers in each bowl?