24over5 divide by 28over15

I know the answer but I just couldn't explain how I got the answer

= 24/5 * 15/28

= (24 * 15)/(5 * 28)

= 360/140

= 18/7

Of course.

Dividing by a fraction is the same as multiplying by the reciprocal.
(24/5) / (28/15) = (24/5) * (15/28)

Multiply that out and reduce, and you get 18/7

do the reciprocal of 28/15 and multiply:
24/5 * 15/28
then, use some algebra wizardry (cross multiply):
6 * 3/7 = 18/7

(24/5)/(28/15)

=

18/7

24/5
-------
28/15

24 x 15
-----------
28 x 5

6 x 3
------
7

18
-----
7

2 4/7