#### Topic: The decision of system of equations with independent variables

Colleagues, very simple question. There are type expressions x1+x5+x19 = 20 x9+x19 = to 40 Me it is necessary numerical methods to find value x1, x19 and so forth That is there is some total of independent variables, I need to find values. And turn listens that before variables there are no coefficients. All would seem simply if to start with the assumption that they are independent. But the situation is quite possible that at presence in the equation simultaneously x1 and x2 they accept other values. Still the question if besides to start with a condition of independence of variables, but that that is probability variables as it is possible to estimate mean value and a standard deviation for each of variables. How these three different types of the equations dare?