Three r's

[используется в разговорной речи] чтение, письмо и арифметика (Reading, wRiting, aRithmetic)

Большой англо-русский словарь

Three r's

noun plural Etymology: from the facetiously used phrase reading, 'riting, and 'rithmetic 1. the fundamentals taught in elementary school; especially reading, writing, and arithmetic 2. the fundamental skills in a field of endeavor

Merriam-Webster's Collegiate Dictionary