So this has to do with permutations and honestly i need an explanation on how i can figure these out.

Well, the answer quite simple there are 4! ways to arrange these numbers...and as 4! = 4*3*2*1 = 24

hence 24 is the correct answer

u can also remember it by theorem of multiplication asin first place (I.e. first code can be any no. out of 4,5,2&7 so 4*

as first place is acquired by a certain no. that leaves three no. to fill third place and when third place I'd occupied it leaves 2 numbers to fill second place and lastly only one no. to fill the last place so it's result will be like 4*3*2*1.

I know this is pretty much confusing but still I tried my best

if anything troubles u here feel free to ask me