Change in temperature and length problem help

[jmb07]

Lead rod and glass rod have same length at 20.8 degrees celsius. The lead rod is heated to 53.4 degrees celsius. At what temperature must the glass be heated so they are the same length?

I know that (change in L)/Lo = (alpha)(change in Temperature)

but I am not sure how to set (change in L of lead) = (change in L of glass) and i don't know what variables to use to solve for T of glass.

Can anyone help me get started on this one. Much appreciated!

 

[Mapes]

What is alpha for lead and glass? Can you write a thermal expansion equation for the glass rod?

 

[jmb07]

they are just some constants...but i don't know how to set these to equations equal to each other to start the problem...

 

[Mapes]

Why can't you just set them equal?