The answer for the question shown in the figure attached is: x∈(-∞,5)∪(5,∞)
The explanation is shown below:
If the domain of the function F is all real numbers, and the domain of the function G is all real numbers, then the domain of the G/F is all real number except the values that make the function F zero, because the division by zero is undefined. Therefore, as you can see in the graph, that value is 5.