Final answer:
To provide an accurate comparison between the sizes of the continental U.S and Australia, we need more context or existing figures on the map. Assuming the U.S. to be roughly 2,800 miles in width, Australia would be around 2,600 miles at its widest point if it is stated to be 200 miles narrower.
Step-by-step explanation:
The student's question appears to center around geographical comparisons of landmass sizes, particularly in reference to the continental U.S. and Australia. Maps, particularly those using Mercator projection, can distort sizes which leads to misconceptions about the actual dimensions of countries and continents. Since the student's question indicates that the continental U.S is about 200 miles wider than Australia, the figure that should replace the question mark on the U.S map would require additional context for a precise answer. Normally, we'd need to know the existing figures on the map to provide a specific number. However, assuming the context invites a direct comparison of width between the continental U.S. and Australia, and if the U.S. is approximately 2,800 miles wide, then subtracting the 200 miles would imply that Australia is approximately 2,600 miles wide at its widest point.