Researching Torque, Current and Flux Density

[monkeyhead]

Homework Statement

For this question you must research, to help you with working out your answer
a) A dc motor develops a torque of 600Nm when its armature carries a current of 30 Amperes. Predict the torque that will be developed when a 12% increase in flux density has taken place and the armaure current is increased to 35 amperes.

The Attempt at a Solution

I have to admit, I'm pretty stumped for this one! I have no clue on what formula links torque,current and flux density together what so ever. I'd imagine that there must be some sort of formula linking all those together right?
I'm not asking for someone to solve this for me but I would gladly appreciate a push in the right direction into where I should be looking! Any suggestions much appreciated
Many thanks
Matt

 

[Hootenanny]

A good place to start for your research would be with http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html#c1" .