Answer
The sharpshooter is $\approx 60.9$m from the target when it is hit.
Work Step by Step
1. Find the unknown angle of the triangle
$= 180 - (70+30)$
$= 180 - 100$
$= 80^{\circ}$
2. Use the sine rule to find $x$
$\frac{x}{sin(30)} = \frac{120}{sin(80)}$
$x = \frac{120sin(30)}{sin(80)}$
by GDC / calculator
$x = 60.9255...$ m
$x \approx 60.9$ m
