step 1
find the equation of the line point A(14,-1) B(2,1)
y=mx+b
m=(y2-y1)/(x2-x1)-----------> (1+1)/(2-14)----------> 2/-12--------> -1/6
m=-1/6
with the point B(2,1) and m--------> find the value of b
1=(-1/6)*2+b-----------> b=1+2/6-------> b=4/3
y=(-1/6)x+(4/3)
we know that
the point C is a solution (x,13)
if the coordinate y is 13
then
13=(-1/6)x+(4/3)---------> 13-(4/3)=(-1/6)x-------> x=(35/3)*(-6)
x=-70
the answer is
the coordinate x of the point C is -70
point C(-70,13)
