Question

A resistor is to have a constant resistance of 30(ohm), independent of temperature. For this, an aluminum resistor with resistance R1 at 0(Celsius) is used in series with a carbon resistor with resistance R2 at 0(Celsius). Evaluate R1 and R2, given that a1=3.9 x 10^-3 degree Celsius^-1 for aluminum and a2=-0.5 x 10^-3degree Celsius^-1 for carbon.

i really don't know how to solve this, so pls. help me...Thanks in advance.