Two wires, each 0.80 mm across, carry 50 N each.

Step 1. Area. $A = \pi(0.40 \times 10^{-3}\ \text{m})^2 = 5.03 \times 10^{-7}\ \text{m}^2$.

Step 2. Steel. $\dfrac{50\ \text{N}}{5.03 \times 10^{-7}\ \text{m}^2} \times \dfrac{2.4\ \text{m}}{2.0 \times 10^{11}\ \text{Pa}} = 1.19 \times 10^{-3}\ \text{m}$.

Step 3. Copper. $\dfrac{50\ \text{N}}{5.03 \times 10^{-7}\ \text{m}^2} \times \dfrac{1.2\ \text{m}}{1.1 \times 10^{11}\ \text{Pa}} = 1.09 \times 10^{-3}\ \text{m}$.