Either the ancient Etruscans were experienced city planners and they invented the art of writing or they were highly skilled engineers and they invented the art of writing. If the ancient Etruscans were bloodthirsty numskulls (as scholars once thought), they did not invent the art of writing. Therefore, the ancient Etruscans were not bloodthirsty numskulls (as scholars once thought). (C, I, H, B)

Translate the following arguments into symbolic form and then use the first thirteen rules of inference to derive the conclusion of each. Use the translation letters in the order in which they are listed.