We have the distributions for the amount of fuel he uses to work and to home, and they say that these are normal distributions. They say that right over here, follows a normal distribution. But here we're talking about the total amount of fuel he has to go to work and to go home. So what we wanna do is come up with a total distribution, home and back, I guess you could say. We could call this work plus home, home and back. If you have two random variables that can be described by normal distributions, and you were to define a new random variable as their sum, the distribution of that new random variable will still be a normal distribution, and its mean will be the sum of the means of those other random variables. So the mean here, I'll say the mean of work plus home, is going to be equal to 20 liters.