Answer:
[tex]4\sqrt{5}[/tex]
Step-by-step explanation:
Prime factorize 20 and 45
[tex]\sqrt{20}=\sqrt{2*2*5}=2\sqrt{5}\\\\\\\sqrt{45}= \sqrt{5*3*3}=3\sqrt{5}[/tex]
[tex]\sqrt{20}-\sqrt{5}+\sqrt{45}=2\sqrt{5}-\sqrt{5}+3\sqrt{5}[/tex]
[tex]=(2-1+3)\sqrt{5}\\\\\\= 4\sqrt{5}\\[/tex]
