Hi!
We can use <u>point-slope form </u>to solve this.

<em> and </em>
<em> will be from one of the points.</em>
<u>First, we have to find </u>
<u>, the slope. We can use the slope equation to get this.</u>

<em>Plug in your points:</em>

Your slope is 
<u><em>Now plug points and slope into point-slope equation. We will use (8, 4).</em></u>

Now, if you want to get it into y = mx + b form, you have to solve for y:



Your equation is 
<u><em>For more information on how to get the equation of a line when given two points, see here:</em></u>
brainly.com/question/986503
$x=3$ I think that’s it... try that
Answer:

Step-by-step explanation:
Two lines are given to us which are perpendicular to each other and we need to find out the value of a . The given equations are ,
Step 1 : <u>Conver</u><u>t</u><u> </u><u>the </u><u>equations</u><u> in</u><u> </u><u>slope</u><u> intercept</u><u> form</u><u> </u><u>of</u><u> the</u><u> line</u><u> </u><u>.</u>
and ,
Step 2: <u>Find </u><u>the</u><u> </u><u>slope</u><u> of</u><u> the</u><u> </u><u>lines </u><u>:</u><u>-</u>
Now we know that the product of slope of two perpendicular lines is -1. Therefore , from Slope Intercept Form of the line we can say that the slope of first line is ,
And the slope of the second line is ,
Step 3: <u>Multiply</u><u> </u><u>the </u><u>slopes </u><u>:</u><u>-</u><u> </u>
Multiply ,
Multiply both sides by a ,
Divide both sides by -1 ,
<u>Hence </u><u>the</u><u> </u><u>value</u><u> of</u><u> a</u><u> </u><u>is </u><u>9</u><u> </u><u>.</u>