Is there any notation to denote the solution of a particular equation?

Question

Let's say that I have an equation:

$$x + 2 = 7 + y$$

If I need the solution for $x$, I can solve it and then use $5 + y$. No problem there.

But say I have an abstract equation. For now I am using the following to denote the equation:

$$eq.A$$

And to express its $x$ solution somewhere else:

$$\textbf{S}(eq.A)_{x}$$

Is there any universal notation to express the abstract notion of equation and its solutions?