The airmail rates to a country are shown.
Type | Mass | Cost |
Letters |
First 20 g | 29k¢ |
Every additional 10 g or less | 9k¢ | |
Postcards | Per piece | 60¢ |
Ethan sent 4 postcards and a letter. The letter weighed 42 g. How much did Ethan pay in total? Give your answer in terms of k in the simplest form.