First I figured out how many photos there are in total, which was by doing 60/.15, since only 15% of the total photos are in black and white. We can already cross out all possibilities that don't have the denominator 400, but we can go a step further by seeing which one is 60/400, or equal to 60/400, which is D. 15×4/100×4 = 60/400.
18 inches or 1 foot and 6 inches multiply 3 feet by 12 and add two to get the width of the door in inches then subtract 20 inches from it to get the difference
