Option #2
11.56 is rounded to 12 because the 6 rounds the 5 to a 6. 11.6 then rounds to 12.
<h2>this is a PICTURE </h2>
<h3>i HOPE IT'S HELP </h3>
If the slope is 5 perpendicular would be -1/5 just flip the slope around
(13 + 20) + 15 = 13 + (20 + 15)