Please provide me a basic general concept $1$st instead of just the answers to the question. I want to know how to apply it$.$ for example, there are multiple pulleys how do I see the difference of the forces between each pulley? I want to be able to apply what I have learnt to other questions not just the answer to this question. Like an short crash course to the whole pulley and spring topic :$).$

Question:

$-$ Determine the tension force at point S$,$ point T and Point U$.$

$-$ Consider that the hook at support A is replaced by $3$ springs in parallel configuration. The springs has stiffness k$1=6\mathrm{.}8$ kN$/$m and k$2=9\mathrm{.}0$ kN$/$m$.$ The total extension of the parallel configuration is $1\mathrm{.}3$m$.$ Determine the spring stiffness of k$(3).$

Correct answers:

$-52\mathrm{.}5,17\mathrm{.}5,131\mathrm{.}5,11\mathrm{.}1230$