It takes 6.5 J of work to stretch a spring 4.1 cm from its unstressed (relaxed)…

It takes 6.5 J of work to stretch a spring 4.1
cm from its unstressed (relaxed) length.
a) How much (in J) spring potential energy is then stored by the
spring?
b) What is the spring constant k in N/m?
c) What if the spring is compressed instead by
4.1 cm from its unstressed length, how much (in J) spring potential
energy is then stored by the spring?
d) How much work (in J) is needed to compress the spring an
additional 4.4 cm?