20 points for step by
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only 100% sure answers!
you so so so much in !

BAD=BCD(base angle ,isosceles triangle)

ABD=CBD(given)

BAD+BCD+ABC=180(angle sum of triangle)

36+36+ABC=180

ABC=108

ABC=ABD+CBD

CBD=108/2

=54

therefore

x=54

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.