Answer
$\frac{5\sqrt {5}}{3}$
Work Step by Step
Distance formula is given as:
$d=\frac{|a \times b|}{|a|}$
Cross product: $a \times b=\lt -5,0,10\gt$
$|a \times b|=\sqrt {(-5)^2+0^2+(10)^2}=5\sqrt {5}$
$a=\sqrt {(2)^2+(-2)^2+(1)^2}=\sqrt {9}=3$
Thus, $d=\frac{5\sqrt {5}}{3}$