A line perpendicular to another has a slope that is the negative reciprocal of the slope of the other line. The negative reciprocal of the original line is –2, and is thus the slope of its perpendicular line
11.5 * 2.3 = large door size large door size / 12 = large door size in feet large door size in feet / 10 = how many large doors can be cut from the board. (you have to round it down if there's a decimal- no 1/2 doors.)
