Do you want an apple?

Let $x$ be the number of apples that Ana bought

Andrew ate $\dfrac{1}{10}x$ , so what was left was $x-\dfrac{1}{10}x=\dfrac{9}{10}x$ .

Elsa ate $\dfrac{2}{9}\left(\dfrac{9}{10}x\right)$ , so what left was $\dfrac{9}{10}x-\dfrac{2}{9}\left(\dfrac{9}{10}x\right)=\dfrac{7}{10}x$

Her mother put $\dfrac{5}{14}\left(\dfrac{7}{10}x\right)$ in the refrigerator, so what was left was $\dfrac{7}{10}x-\dfrac{5}{14}\left(\dfrac{7}{10}x\right)=\dfrac{9}{20}x$

That means that what was left on the table was $\dfrac{9}{20}x$ , and that is equal to $9$ , so we have

$\dfrac{9}{20}x=9$

It follows that,

$x=$ $\color{#D61F06}\boxed{\large 20}$