Quote: 34 1/2 inches minus 33 7/8 inches
There's a couple ways you can do this.
1) you can convert the whole thing to 1/8's of an inch.
34 1/2 inches = 8x34 + 8x(1/2) = 276 (1/8 inches)
33 7/8 inches = 8x33 + 7 = 271 (1/8 inches)
so 34 1/2 - 33 7/8 inches = 276 - 271 (1/8 inches) = 5 (1/8 inches) = 5/8 inch
2) you can notice that 7/8 > 1/2 so you need to borrow a 1 from the 34.
then you have 34 1/2 inches - 33 7/8 inches = 33 + 1 1/2 inches - 33 7/8 inches = 1 1/2 - 7/8 inches
now you convert the 1 1/2 to 1/8ths to get
1 1/2 - 7/8 inches = 12/8 - 7/8 inches = 5/8 inches
+6248 
