First of all, must underline that the original word "section" – since from the Latin: sectio aurea – represents a Portion of a Unit; therefore the main symbol Phi should be referred to the decimal irrational number .618… and not to its counterpart 1.618…, which is phi: a unit + a portion added won't be a section ( the later "ratio" definition comes more flex­i­ble, though).

This being said, it's worth to be introduced an alternative quick way to figure out their ratio. It is such as they can be applied to any number or value N, almost like a unique parameter, simply al­ter­nat­ing the modes, always getting:

N × f = N / j and evenly N / f = N × j
That brings to:
F × j = 1.
Conceptually,
the Percentage of [a Unit + the same Percentage of itself] is eq. One.

Then each sub­se­quent re­duc­tion or se­quen­tial in­crease re­tain a con­stant Pro­por­tion be­tween the parts (or el­e­ments), in
a per­en­ni­al re­cip­ro­cal bal­ance.