Sherina's error lies in her approach to solving the equation \( x - 56 = 230 \). She should have added 56 to both sides of the equation instead of subtracting it. The correct steps are as follows:
- Start with the original equation: \[ x - 56 = 230 \]
- To isolate \( x \), add 56 to both sides: \[ x - 56 + 56 = 230 + 56 \]
- This simplifies to: \[ x = 286 \]
So, Sherina's mistake was in the operation she applied to both sides of the equation; her solution of \( x = 174 \) is incorrect. The correct solution should be \( x = 286 \). To summarize, she should have added 56 to both sides of the equation to solve for \( x \) correctly.