Tension - two objects and a string

[phish]

Homework Statement

An object 1 of mass 5 kg is attached to object 2 of mass 7 kg with a string. The 5 kg object is pulled up with a 67 N force - what is the tension in the string.

Homework Equations

F= ma

The Attempt at a Solution

Since object 1 has an external force of 67 N acting upon it, that force should be subtracted by the weight of object 1: (5)(9.8) = 49 N
67 - 49 = 18 N

Object 2 just has its weight force acting upon it: (7)(9.8) = 68.6 N

I've calculated the forces acting on the objects - but I'm not sure how to calculate tension from here.

 

[rl.bhat]

Find the acceleration of m1 and m2 due to applied force.
What is the net force acting on m2?
What is its equate it to the combined acceleration to find T.