To determine who is correct, we need to analyze the problem that Austin worked on. However, since the actual problem isn't provided in your question, I can't definitively say whether Austin or Lisa is correct.
If you could provide the specific problem or equation they were working on, I would be able to help you evaluate the answers and determine whether Austin's answer of \( x = 7 \), Lisa's answer of \( x = 1 \), or both answers are incorrect. Please share the details of the problem!