Final answer:
The sentence 'I ate pancakes, but my sister had waffles' should retain its comma because it is a compound sentence with two independent clauses joined by the coordinating conjunction 'but'. Commas are appropriately used in such cases, following the grammatical rules for combining independent clauses.
Step-by-step explanation:
The sentence in question, "I ate pancakes, but my sister had waffles", is actually a proper compound sentence because it contains two independent clauses connected by the coordinating conjunction 'but'. There are specific rules to follow when determining whether a comma should be removed or included in a sentence. According to the rules of proper comma usage, one should:
In this case, because we have two independent clauses—'I ate pancakes' and 'my sister had waffles'—separated by the conjunction 'but', the comma preceding 'but' is correctly placed and should not be removed. Therefore, no action is required regarding the comma in the given sentence.