Finding an absolute value

Question

Instruction says

Find |3 - $\sqrt{10}$|

Given answer is $\sqrt{10}$ - 3

I cannot give an explanation.

Answer 1

$3^2=9<10$, so $3<\sqrt{10}$. This means that $3-\sqrt{10}<0$.

Then, by the definition of absolute value, $|3-\sqrt{10}|=-(3-\sqrt{10})=\sqrt{10}-3$