The drawing shows three identical springs hanging from the ceiling. Nothing is attached to the first spring,

Question:

The drawing shows three identical springs hanging from the ceiling.
Nothing is attached to the first spring, whereas a 4.50-N block hangs from the second spring. A block of unknown weight hangs from the third spring. From the drawing, determine
(a) The spring constant (in N/m) and
(b) The weight of the block hanging from the third spring.