Two packs \(\mathrm{A}\) and \(\mathrm{B}\) of mass \(m_{A}=2.2 \mathrm{~kg}\) and \(m_{B}=2.8 \mathrm{~kg}\) are connected by an inextensible rope of negligible mass. Pack A rests on an inclined plane \(25^{\circ}\) relative to the ground plane and is attached at the lower end to a spring of elastic constant \(k=55.0 \mathrm{~N} / \mathrm{m}\) positioned at the beginning of the inclined plane. The topmost end of pack A is attached to a pulley from which pack \(B\) hangs vertically. The entire system is at rest. Draw the system highlighting the forces involved and calculate the elongation \(\Delta l\) of the spring.