Adding and subtracting mixed #'s - step 1: create common denominators if they are not there! (2) Step 2: Add or subtract (you can add/subtract the whole #'s first and then the fractions or the fractions and then the whole #'s or vice-versa...doesn't matter).
NOTE: You may need to borrow "from the wholes" on some of the subtraction problems (see example below!)

Example: 1 1/2 - 7/8 = _____

step 1 - common denominators: 1 4/8 -7/8 = _____

Ok, so you can't take 7/8 away from 4/8 so we're going to have to borrow some 8ths from our 1 whole...1=8/8 which we can combine with the 4/8 we already have....this would make our number sentence look like this:

12/8 - 7/8= 5/8 (the 12/8 is is the 8/8 + 4/8 from above)