Once the problem is defined properly, the solution to the problem is easy...the solution is the flip side of the definition. The flip side of the definition of the problem is the solution to the problems. Once the root causes of the problem are identified, the solution to the problem is to supply or remove the inputs and processes that are necessary to get the desired results.
Before starting on the action to modify the inputs and processes (remove or provide), the solution must be put to the test first. The problem-owner must ask this question, "If these deficiencies are remedied, will it solve the problem and generate the desired outcomes?" Often, the solution is speculative and one knows for sure. It is worth asking the question and applying logic to determine before-hand if the problem will be solved with the solution proposed. It is better to anticipate in advance any shortfalls in the solution so as to avoid delays ,disappointment, and extra incurred costs.
In every case, a problem is solved when the right combination of inputs and processes are present. When the right combination of inputs and processes are present, the problem will be solved. Whether or not the precise combination is required depends on the circumstances. Remember that Edison struggled to invest the incandescent light bulb for thousands of trials until he found just the right combination of inputs. For some problems, they crack when only the exact right combination of inputs are present. For other problems, they get progressive better the more the right inputs are added and the wrong inputs are removed. Try a solution and see it effect on the problem. Sometime, small changes can make a big difference...especially for those problems dealing with human relationships.