Hello!!!

Hope you are doing great!!!

given, edge of a cube= a

Workdone=force * displacement

force=1/4πε0 *q^2/r^2

displacement for the given cube=a/2

by substituing the values, We get

Workdone for 8 charges to be moved is

8(1/4πε0 *q^2/a^2)*a/2

by solving the above equation we get,

W=q^2 /πε0a Joules

Hope it helps!!!