Adding "days an hours" cells together

I know nothing about excel, I'm trying to create a sheet for helping with a game.

https://preview.redd.it/8x595g3urege1.png?width=813&format=png&auto=webp&s=89dd02e8b8ed3c9837cad7323dd52dc0c7fe9cd1

"1 days 6 hours" starts at D43. ChatGPT gave me the formula

=INT(D42*300/86400) & " days " & INT(MOD(D42*300/3600,24)) & " hours"

which is giving the amount of time needed to obtain 360 energy which generates every 5 minutes.

Now I'm trying to add these together into another cell to show the total time. ChatGPT gave the formula

=INT(SUM(D43:F43)*300/86400) & " days " & INT(MOD(SUM(D43:F43)*300/3600,24)) & " hours"

but this just gives "0 days 0 hours." I tried messing around a few different ways but it just says 0 in whatever format.

Version 2412, subscription