How much work must be done to increase the speed of an electron:

$($a$)$ From $0\mathrm{.}18$c$0\mathrm{.}18$c$0\mathrm{.}18$c to $0\mathrm{.}20$c$0\mathrm{.}20$c$0\mathrm{.}20$c$,$ and

$($b$)$ From $0\mathrm{.}92$c$0\mathrm{.}92$c$0\mathrm{.}92$c to $0\mathrm{.}94$c$0\mathrm{.}94$c$0\mathrm{.}94$c$?$

Note that the speed increase is $0\mathrm{.}02$c$0\mathrm{.}02$c$0\mathrm{.}02$c in both cases. Provide your answers in keV.