To answer this you will use the unit rate of 80 pixels per square inch with each of the the pixels given. So, for example, Nick's computer contains 409600 pixels, so to find the number of square inches for his screen divide the total number of pixels by 80. This will give you a number of inches for his computer screen (409600/80=5120 inches). For Matt, you will divide 640000 by 80 and get 8000 inches. To find the answer subtract 8000 and 5120 to get 2880 inches. This answer is not really reasonable for the width of the computer screen, but based on the info, this is how you find the answer.