Question

Holly finds that (11m – 13n + 6mn) – (10m – 7n + 3mn) = m – 20n + 9mn. What error did Holly make?

Answer 1

thoughts? as a major hint, notice how there's a negative sign in front of (10m – 7n + 3mn) which means it needs to be distributed across all the terms within the parentheses first. once you do that, it should be clearer where she made the mistake.