A carbon resistor (temperature coefficient of resistance $-5 \times 10^{-4}\ {}^\circ\text{C}^{-1}$) is joined in series with a copper wire (temperature coefficient $4 \times 10^{-3}\ {}^\circ\text{C}^{-1}$). The total resistance is $9\ \text{k}\Omega$, and it does not change when the temperature changes a little. The resistances of the carbon and of the copper are