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 as.....in 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

Differentiate both sides with respect to

:

When

, you have

For part (b), we now assume that

and

are functions of an independent variable, which we'll call

(for time). Now differentiating both sides with respect to

, we have

where the chain rule is used on the right side. We're told that

is decreasing at a constant rate of 0.1 units/second, which translates to

. So when

, you have



where the unit is again units/second.
Answer:
(a) 12:5
(b)12:7
Step-by-step explanation:
HOPE i helped!