Early alphabets, such as the semitic, established shapes for sounds of consants. the greeks added vowels and spread among greek speaking populations.
trade

literacy

schools

other languages

wealth

The Greek language is spoken on the Balkan Peninsula, from about 3 millennia BC, perhaps earlier, making the Greek language the yard of the oldest living languages in the world. The Greek alphabet was derived from the Phoenician script and is based on the Latin and Cyrillic alphabet. It is created by adding vocals to the already existing consonants of the older Semitic alphabet, characterized by a small number of letters, which facilitates wider usage. Although, with the advent of this alphabet, literacy has not been fully implemented, scientists believe that literacy among people has spread more than ever before.

The answer is: Literacy

6 units. ab and lo are congruent sides, and if ab= 6 units, then lo would be the same.