A retailer has two markets, 1 and 2. Demand 1 follows normal distribution with mean 100 and standard deviation 12.4. Demand 2 follows normal distribution with mean 110 and standard deviation 16.7. The retailer needs to know the mean and standard deviation of the TOTAL demand. Please describe the conceptual analysis process to find out these two parameters by using simulation.

I am trying to understand how this is done using excel, the other responses to the same question on this site do not offer a step-by-step process to the answer. I am not looking for a quick answer, I just want to know how to arrive at the answer using simulation in excel so I can understand. Please explain the process and the steps