Answer:
[tex]\huge\boxed{5(\sqrt{144}-\sqrt{64})=20}[/tex]
Step-by-step explanation:
[tex]\sqrt{a}=b\iff b^2a\ \text{for}\ a\geq0\ \text{and}\ b\geq0[/tex]
[tex]5(\sqrt{144}-2\sqrt{64})=(*)\\\\\sqrt{144}=12\ \text{because}\ 12^2=12\cdot12=144\\\sqrt{64}=8\ \text{because}\ 8^2=8\cdot8=64\\\\(*)=5(12-8)=5(4)=20[/tex]
