Question 796212
The area of a parallelogram, just like a rectangle, is base length times height length.


A for area
b for base length
h for height
{{{b=h+9}}}, from description


{{{A=b*h}}}
The question is, what is the height.   (You already were given the base value).
{{{h=A/b}}}
{{{h=A/(h+9)}}}, using the description of base from the problem.

Use the given values.
{{{h=52/(h+9)}}}
{{{h(h+9)=52}}}
{{{h^2+9h=52}}}
{{{highlight(h^2+9-52=0)}}}  AND THE LEFT SIDE IS FACTORABLE.


{{{(h-4)(h+9)=0}}}
We must accept the positive solution, so {{{highlight(h=4)}}}.