Question 1023111
2x and 3x are these two adjascent sides.
{{{2*2x+2*3x=50}}}
{{{4x+6x=50}}}
{{{10x=50}}}
{{{x=5}}}


The longest side, if a base for a triangle, is {{{3*x=3*5=15}}}.
This base does not need to be dedicated just to a triangle; but can be just the side perpendicular to the altitude  (10 cm) of the parallelogram.


With base 15 cm and height or altitude 10 cm, the area for the parallelogram is  {{{15*10=highlight(150*cm^2)}}}.