When dividing fractions, you switch the denominator and numerator on the second fraction, and change the divided sign to a multiplication sign.
So,
251 -3
------ / --------
4 8
becomes
251 8
----- x -----
4 -3
251 x 8= 2008
4 x -3= -12
Now, divide 2008 by -12.
2008 does not go into -12 evenly (the answer would be -167.333333333333. The 3s would go on forever)
2008/12 is equivalent to 502/3
So, 251/4 divided by -3/8 is around 167 1/3, or 502/3
