What is the correct solution for 80 in roman numerals LXXX or XXC?

THE ANSWER IS-LXXX BECAUSE50

L =

X=10(SO  X+ X+ X= 30[10+ 10+ 10= 30]

LXXX=(L +X+ X+ X= LXXX[50+ 10+ 10+ 10 =80]

HOPE YOU UNDERSTAND!!!1