23x and 9x are alike terms so
23x-9x
14x
Hey there,
Your question states: <span>Find the perimeter of a square whose sides are 7.
When finding the perimeter, we need to multiply each side because it is a square. So 7 times 4 would be 28
~Jurgen</span>
we know that
If two lines are perpendicular, then the product o their slopes is equal to minus one
so

Step 1
<u>Find the slope of the given line</u>
we have

-------> 
This line is parallel to the y-axis
so
the perpendicular will be parallel to the x-axis
Step 2
The equation of the line perpendicular to the given line is the y-coordinate of the given point
Point 
the equation is

therefore
<u>the answer is</u>

see the attached figure to better understand the problem