hint:

Make sure to change the temperatures to Celsius or Kelvins first so that you can use the coefficient for linear expansion.
The equation for linear expansion is the following:

eqnarray7

tex2html_wrap_inline53 is the change in length
tex2html_wrap_inline55 is the coefficient for linear expansion
tex2html_wrap_inline57 is the length of the material
tex2html_wrap_inline59 is the change is temperature