Two identical springs hung from a ceiling have different masses. The first spring is 1 kg with a total length of 6 cm. The second spring is 1.5 kg and is 7 cm in length. The displacement between the two springs is 1 cm. Find the spring constant k.
(A) 2 N/cm
(B) 5 N/cm
(C) 10 N/cm
(D) 20 N/cm
I started solving each equation for k, but ended up with different values. Thanks in advance.