The airmail rates to a country are shown.
Type | Mass | Cost |
Letters |
First 16 g | 28a¢ |
Every additional 8 g or less | 11a¢ | |
Postcards | Per piece | 70¢ |
Riordan sent 4 postcards and a letter. The letter weighed 21 g. How much did Riordan pay in total? Give your answer in terms of a in the simplest form.