There’s an article at the NRICH website https://nrich.maths.org/2515 which gives you some of the history. The Ancient Egyptians (going back about 3800 years) had a complicated system based on reciprocals, so instead of writing, say, 3/5 they would write it as 1/2 + 1/10. The Babylonians (going back a little longer) used a system in which everything was based on 60-ths. In fact, that’s the reason we still divide time up in that way, 1 minute = 1/60 of an hour, 1 second = 1/60 of a minute. Try expressing 3/5, 1/2 and 1/10 all in terms of something/60 to check what I said about 3/5 being equal to 1/2 + 1/10 !