Question

plz tell me this answer plz​

Answer 1

$= 9 \sqrt{5} - 4 \sqrt{5} + \sqrt{125} \\ = 9 \sqrt{5 } - 4 \sqrt{5} + \sqrt{25 \times 5} \\ = 5 \sqrt{5 } + 5 \sqrt{5 } \\ = (10) \sqrt{5} \\ = 10 \sqrt{5}$