Answer :

BananaOnYourFace
the answer is 0.119
you can either round the denominator (bottom number) toa c ommon number (in this case 8) and multiply the numerator with the same number (4 x 2 = 8 so 21 x2 = 42) making it 5/8 divied by 42/8   (5 divided by 42) 

or you can work it out to decimals making 5/8 0.625 and 21/4  5.25 (0.625 divided by 5.25)
icedraptor88
Mulitply by the reciprocal, 5/8 divided by 21/14 is the same as this:

5/8 multiplied by 14/21

The answer is 5/12.