When two variables are related then one of them may be independent while the other one is dependent on the former variable.
Any kind of change in dependent variable does not impacts the independent variable whereas any change in independent variable certainly alters the other variable which is dependent on the variable being deliberately altered.
Here, in this case the statement declares that 'the use of honey may reduce coughing in children', we infer that using honey can bring down the frequency of coughing in children.
At the same time if we any how change the frequency of coughing then the involvement of change in the factor 'honey' is absurd.
So the question here is just simply what percentage is 10 out of 50 correct? You would basically just do 10/50 times 100 which will give you 20 percent as your answer.