here help u 3/5
Step-by-step explanation: u want see my work?
Let, coordinate of point A' is (x,y).
Since, A' is the symmetric point A(3, 2) with respect to the line 2x + y - 12 = 0.
So, slope of line containing A and A' will be perpendicular to the line 2x + y - 12 = 0 and also their center lies in the line too.
Now, their center is given by :

Also, product of slope will be -1 .( Since, they are parallel )

x = 2y - 1
So, 
Also, C satisfy given line :

Also,

Therefore, the symmetric points is
.
If we discuss this as if it is a triangle then the "rise" is the vertical side and the "run" is the adjacent side.
So the ratio of the rise to the run is 8 / 15 which equals
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0.5333333333
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To find the angle of this roof pitch we look up the arc tangent of
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0.5333333333
</span>
</span>
</span>
and we find that is 28.072 Degrees
Trigonometry Calculator:
http://www.1728.org/trigcalc.htm
Since you have parentheses, you will first multiply (q-2)*(r-3) which equals (qr+6). So now its simplified to p(qr+6) which equals pqr+p6.