principle of superposition

Problem 244
A homogeneous bar with a cross sectional area of 500 mm² is attached to rigid supports. It carries the axial loads P₁ = 25 kN and P₂ = 50 kN, applied as shown in Fig. P-244. Determine the stress in segment BC. (Hint: Use the results of Prob. 243, and compute the reactions caused by P₁ and P₂ acting separately. Then use the principle of superposition to compute the reactions when both loads are applied.)