The same way you do for simple algebra. The complication on each side don't change the rules; you are still doing algebra.

Sure. There are other applications of arithmetic, but algebra without arithmetic is impossible. A broad knowledge of arithmetic is essential for mastery of algebra.

Michael Kapovich has written:

'The generalized triangle inequalities in symmetric spaces and buildings with applications to algebra' -- subject(s): Symmetric spaces, Rings (Algebra), Geometric group theory, Lorentz groups, Linear algebraic groups, Semisimple Lie groups

Try Painless Algebra (book by Baron's).

Use equation.