How do you add sqrt45 + sqrt125?

The answer is $8 \sqrt{5}$
$\sqrt{45} + \sqrt{125} =$
$\sqrt{9 \cdot 5} + \sqrt{25 \cdot 5} =$
$\sqrt{{3}^{2} \cdot 5} + \sqrt{{5}^{2} \cdot 5} =$
$3 \sqrt{5} + 5 \sqrt{5} =$
$\sqrt{5} \left(3 + 5\right) = 8 \sqrt{5}$