Please help me the following question.

1. When ki =30 [N/m], k2=20 [N/m], k3=25 [N/m], solve the following problems without skipping logical steps. You must write down all the steps necessary using the right variables. (1) Find equivalent spring constant k12 when you combine k1 and k2 k3 (3) Find the change of x1 and x2 when the force F= 1 kN is applied. F=100N (2) Find equivalent spring constant k123 when you combine k12 and k3