Part A
Count out the number of squares in Model A, and you should count out 36 squares. Or you can use a shortcut to multiply the length and width to get 6*6 = 36. Divide this over 4 which is the same as multiplying by 0.25 (because 1/4 = 0.25) to get 36/4 = 9. So you should shade in exactly 9 little squares
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Part B
There are 9 smaller rectangles. One-third of that count is 3 since (1/3)*9 = 9/3 = 3. So you should shade in 3 smaller rectangles
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Part C
Compare the two shaded areas. You should find that the shaded area in model B is larger since the widths are about the same, but the height of model B is larger in terms of shaded area. See the attached image below.
Another way to see this is to consider the fact that both model A and model B have the same area overall. Let's say the area is 100 square units. This would mean the red shaded region (see attached figure) is 0.25*100 = 25 square units and the blue shaded region is approximately (1/3)*100 = 33.33 square units, proving that model B's shade area is larger compared to model A's shaded area.