Find mass given acceleration and upward force

1. Oct 14, 2011

zonesthesia93

1. The problem statement, all variables and given/known data
Find the mass of the body when:
upward force is 10N
downward force unknown (mg N)
acceleration 5ms^-2 downwards

2. Relevant equations
F=ma
W=mg

3. The attempt at a solution
Need to work out the resultant force?? Then find the mass from there...

Thank you!

2. Oct 14, 2011

DiracRules

That's correct.
Remember that $\sum \vec{F}=m\vec{a}$