check the picture below.
so, what does that mean? well, the median GP, gets cut by the point O, at a ratio of 2:1, the same is true for the other medians btw, EN and FM.
that means GO is twice as large as OP.
since we know that OP is 20 -x , let's use that then.
[tex]\bf GO:OP\qquad \cfrac{GO}{OP}\qquad 2:1\qquad \cfrac{2}{1}=\cfrac{GO}{OP}\implies \cfrac{2}{1}=\cfrac{4x-8}{20-x}
\\\\\\
40-2x=4x-8\implies 48=6x\implies \cfrac{48}{6}=x\implies \boxed{8=x}\\\\
-------------------------------\\\\
OP=20-(8)[/tex]
