How Do You Calculate R1 and R2 for Temperature-Independent Resistance?

[frozen7]

A resistor is to have a constant resistance of 30(ohm), independent of temperature. For this, an aluminium 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 $$\alpha 1$$ is 3.9 x 10^-3 for aluminium and $$\alpha 2$$ is -0.5 x 10^-3 for carbon.

Can anyone give me some clues to solve this question? Thanks in advance.

 

[Curious3141]

Start with the definition of alpha.

 

[lightgrav]

Resistances in series ...
there's a way to represent these with a single equivalent resistance ...