Magnitude of acceleration help

i am having trouble with following problem and need some help in solving it, it will be much appreciated, thank you in advance

If an astronaut throws a tool with a force of 16.0 http://session.masteringphysics.com/...?units=%5Crm+N, what is the magnitude of the acceleration http://session.masteringphysics.com/render?var=a of the astronaut during the throw? Assume that the total mass of the astronaut after she throws the tool is 80.0 http://session.masteringphysics.com/...units=%5Crm+kg.

thanks again