Answer
The astronaut will move at a speed of 0.105 m/s relative to the space station in the opposite direction from the tool.
Work Step by Step
$m_1v_1 + m_2v_2 = 0$
$m_2v_2 = -m_1v_1$
$v_2 = \frac{-m_1v_1}{m_2}$
$v_2 = \frac{-(2.25~kg)(3.20~m/s)}{68.5~kg}$
$v_2 = -0.105~m/s$
The astronaut will move at a speed of 0.105 m/s relative to the space station in the opposite direction from the tool.
