This is one of the first differential equations that you will learn how to solve and you will be able to verify this shortly for yourself. It is often useful given a group of values to know what value will yield a certain average when added to the group. If we said x6 then the equation is not solved because 627 is not true.
Or derive the formula yourself with the given equation.
In other words we want to move everything except x or whatever name the variable has over to the right hand side. The process of finding the value of the variable is called solving the equation. The first of these rules that students learn in science math or chemistry classes is the rule of symmetry which says that any operation performed to one side of the equation must also be performed to the other. Solve for x means find the value of x that would make the equation you see true.