doing sth. is very easy, very simple: это
сделать X ) - - it's as easy as pie (to do X)
it's (doing X is) as easy as one, two, three (as can be)
nothing could be simpler (easier) than doing X
it's (doing X is) the easiest (simplest) thing in the world (on earth).
«Дураку понятно, Сивого засудить проще простого: ...у (его) мамаши сумку потерпевшей изъяли...» (Черненок 2). "Even a fool can see that it's as easy as pie to put Vasya Sivy away: . the victims purse was found at his mother's " (2a)
«Ну, с талантами, знаете ли, расправляться проще простого» (Войнович 4). "But, you know, nothing could be simpler than making short work of talented people" (4a)
Она не посмела отпроситься у брата. В другое бы время проще простого: сбегаю на часик в клуб, ладно? А сегодня язык не поворачивается (Абрамов I). .. .She could not get up the courage to ask her brothers permission At any other time it would be the simplest thing in the world I'm going over to the club for an hour, okay9 But today she could not work up the nerve (1a)
Была для Митьки несложна и пряма жизнь... Голоден - можно и должно украсть... износились сапоги -проще простого разуть пленного немца... (Шолохов 3). For Mitka life was straight and uncomplicated .If he was hungry, he could and should steal...
if his boots were worn out, the simplest thing on earth was to take a pair off a German prisoner. (3a)Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. С.И. Лубенская. 2004.