What is the mass of the second child on a seesaw?

[jessica.so]

Homework Statement

Two children balance on a seesaw. One, with a mass of 30 kg, is seated 2.0 m from the pivot. The other is seated 2.5 m from the pivot. What is the mass of the second child?

Homework Equations

N/A

The Attempt at a Solution

I drew the diagram of the two children and I found the force of gravity acting on the first child:
Fg=mg ; Fg=(30 kg)(9.8 m/s/s) ; Fg = 294N

I know that the Net Force would be 0 because the seesaw is balanced.
And then...I don't know what to do...

 

[Rake-MC]

Okay, so they both have the same acceleration acting on them g = 9.81ms^{-1}

However they both have torques created by the distance from the pivot point.

We know that \tau = Fr

So we're saying that (30)(9.8)(2.0) = (m)(9.8)(2.5)

 

[jessica.so]

ohh okay! and then you would just isolate and...yaa! Thanks so much for your help! I really really appreciate it!