Put the 5 over 1 (5/1) 
Next take 5/1 subtracted it from 7/8
To do that you need a common denominator 
So take the 5/1 time 8 to the denominator and numerator 
 You'll get 40/8 
NOW TAKE 40/8 subtract 7/8 
You can only subtract the numerator 
40-7= 33 
The denominator stay the same 
SO THE ANSWER IS 33/8