Typically a scaffolding has two ropes to support it. One
on the left most side while the other one is on the right most side. Based on
equilibrium rule, the summation of forces must be 0. The downward force is the
weight of person and scaffolding, while the upward force are the tensions on
the two ropes, hence:
Weight person + Weight scaffolding = 2 * Tension
500 N + Weight scaffolding = 2 * 400 N
Weight scaffolding = 300 N
