pellucid
lucid
plain as Dunstable highway
open-and-shut
cut and dried
easy peasy
forthright
plain sailing
nothing to it
decomplication
uncomplication
supersimple
shine
uncomplicated
ultrasimple
spell out
simplistic
loud and clear
spell things out
haplo-
onefold
superclear
purely and simply
clear as day
eathy
luminous
mick
nimps
there's nothing to it
downhill
easyish
easy peasy lemon squeezy
ultraclear
straightforward
smooth
plainful
lor
crystal clear
easy as pie
piss-easy
apparent
easy as falling off a log
simple as kiss your hand
pimpsy
unambiguous
basical
hyperclear
crystal
dizzy
bring home