First off, let's keep in mind that perpendicular lines have negative reciprocal slopes, hmmm so what's the slope of y = 2x + 5?
well, notice, that equation is in slope-intercept form, thus

.

so, we're really looking for the equation of a line whose slope is -1/2 and runs through 1,4.
Answer:
≈ 5.36
Step-by-step explanation:
If we have a triangle in which the angle measure of it being broken down are the same, that means that the legs in which the angle measures are the same will have the same length.
If we already know that DE ≈ 9.28, then we can subtract this from 20 and divide by two to get BD, which is equal to EC.

However, I'm not 100% sure about this answer.
Hope this helped (and I hope I'm right)
13 143rds would be written as 13/143.