Simplify the following text for a Grade 13 native English-speaking person.
Original: As South Australia ( 1836 ) , Tasmania ( January 1855 ) and Victoria ( May 1855 ) obtained responsible government , their Lieutenant-Governors were replaced by Governors .
Simplified: As they became independent , South Australia in 1836 , Tasmania January 1855 and Victoria May 1855 replaced their Lieutenant-Governors with Governors .