Question 1154202
.


            The solution by  @mananth is  INCORRECT,  unfortunately.


            So I came to provide a correct solution.


            I copied and pasted the solution by @mananth, and then fixed/edited it,  where required.



<pre>
D is the mid of BC

D(x1,y1) 

x1= (-3-5)/2 =-4

y1= (8+4)/2 =6

slope of BC = (8-4)/(-3+5)= 2

Slope of AD = -1/2 ( it is perpendicular to BC)    <<<---=== it is first place, where I edit the solution by @mananth.
                                                             Surely, it implies changes in all lines that follow . . . 

Equation of  AD  is  (y-y1) = m(x-x1)

(y-6) = -1/2  * (x+4)

2y - 12 = -x - 4

2y = -x + 8

y= -1/2*x + 4

compare with y =  mx + b

m = -1/2 and b = 4

m+b = -1/2 + 4 = {{{3}}}{{{1/2}}} = 3.5.        <U>ANSWER</U>
</pre>

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If you really want to learn on how to solve such problems on your own, &nbsp;in this site there are lessons that cover this subject.


The lessons are

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Find-the-slope-of--a-straight-line-passing-through-two-given-points.lesson>Find the slope of a straight line in a coordinate plane passing through two given points</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Equation-for--a-straight-line-having-a-given-slope-and-passing-through-a-given-point.lesson>Equation for a straight line having a given slope and passing through a given point</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Solving-problems-related-to-the-slope-of-a-straight-line.lesson>Solving problems related to the slope of a straight line</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Equation-for--a-straight-line-passing-through-two-given-points.lesson>Equation for a straight line in a coordinate plane passing through two given points</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Equation-for--a-straight-line-parallel-to-a-given-line-and-passing-through-a-given-point.lesson>Equation for a straight line parallel to a given line and passing through a given point</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Equation-for--a-straight-line-perpendicular-to-a-given-line-and-passing-through-a-given-point.lesson>Equation for a straight line perpendicular to a given line and passing through a given point</A> (*)

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/Advanced-problems-on-finding-equations-for-straight-lines-.lesson>Advanced problems on finding equations for straight lines</A> 


&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/geometry/OVERVIEW-of-lessons-related-to-the-slope-of-a-straight-line.lesson>OVERVIEW of lessons related to the slope of a straight line</A> 


The most relevant to your current problem is the lesson marked &nbsp;(*) &nbsp;in the list.

So start from this lesson.


But if you want to learn the subject in all its aspects, &nbsp;you need to read all these lessons.


Consider them as your textbook, &nbsp;handbook, &nbsp;tutorials and &nbsp;(free of charge) &nbsp;home teacher.