Define the total percentage abundance.

The total percentage abundance of all isotopes of an element is $100\%$.

If the abundance of $^{69}\text{Ga}$ is $x\%$, then the abundance of $^{71}\text{Ga}$ is the remaining percentage.

The expression for the abundance of $^{71}\text{Ga}$ is $\boxed{(100 - x)\%}$.

The Relative Atomic Mass (RAM) is calculated using the formula:

Given:
RAM = 69.72
Mass of $^{69}\text{Ga}$ = 69
Mass of $^{71}\text{Ga}$ = 71
Abundance of $^{69}\text{Ga}$ = $x\%$
Abundance of $^{71}\text{Ga}$ = $(100 - x)\%$

Multiply both sides by 100:

Combine like terms:

Rearrange the equation to solve for $x$:

The percentage abundance of the $^{69}\text{Ga}$ isotope is $\boxed{64\%}$.