At equilibrium:
(i) R = F1 + F2 i.e. 5 = F1 + F2 ......(1) and
(ii) F1 × 3 = F2 × 7...... (2)
From equation (1), F2 = 5−F1. Substituting for F2 in equation (2) gives:
F1 × 3 = (5 − F1) × 7
i.e. 3F1 = 35 − 7F1
10F1 = 35
from which, F1 = 3.5 kN
Since F2 = 5 − F1, F2 = 1.5 kN
Thus at equilibrium, force F1 = 3.5 kN and force F2 = 1.5 kN