This is quite simple. Just solve the the fractions first then model it. It solve you need to make sure the denominator of both fractions that your either adding or subtracting, are the same or else it won’t work. For example, number 5, 5 3/4 needs to become 5 6/8, which is the same thing but only now you can subtract it to 3 1/8.
Once your down with that just shade in the boxes. If you have a whole number in front of that fraction fill in the number of boxes that number represents. When you get to the fraction part of the mixed number, just fill in a small portion of what the numerator states. Hope this helps