What equal length of an iron wire and a copper-nickel alloy wire, each of 2 mm diameter connected parallel to give an equivalent resistance of 3 Ω?…

What equal length of an iron wire and a copper-nickel alloy wire, each of $\displaystyle 2$ mm diameter connected parallel to give an equivalent resistance of $\displaystyle 3 \Omega$ ? (Given resistivities of iron and copper-nickel alloy wire are $\displaystyle 12 \mu \Omega \mathrm{~cm}$ and $\displaystyle 51 \mu \Omega \mathrm{~cm}$ respectively)