Lily begins by solving the equation 4(x – 1) – 3(x + 5) – 11. Then she realizes that x = 11, which is the problem’s solution. But she does not understand why this partial solution is correct. The reason is that she is not solving the equation properly, and the problem is not well-posed. That is why she is not solving the problem correctly. She needs to make sure that her solution is well-posed before she can move on to the next step.