1. Robininvites 81 boys and 71 girls to his birthday party. How many friends did he invite?   2. There are 12 cakes. Each cake is cut into 8 pieces. How many pieces are there in all?   3. There are 84 sandwiches to be arranged equally in 3 trays. How many sandwiches will there be in each tray?   4. Dad has planned 21 games for the party. Each game would have 3 winners. How many prizes would Dad give away?   5. Mom places 16 paper plates on the table in 9 rows. How many paper plates are there in each row?