21/2 divided by 3/4? show your work.

First you make 2 1/2 into a improper fraction. 
2 1/2 = 5/2

Next you change the division into multiplication and do a recipricol with 3/4 (which changes it into 4/3)
5/2 x 4/3

Now you multiply
5/2 x 4/3 = 20/6

Simplify
20/6 = 10/3

Answer is 10/3 or 3  1/3

hope this helps