So the perimeter is the measurement of the shape all around. I marked the perimeter in green.
Let's use <em>l</em> for the unknown side.
Since the equation to find the perimeter of a rectangle is
(<em>p </em>= perimeter, <em>l </em>= length, <em>w </em>= width)
<em>p </em>= <em /><em>l </em>+ <em>l </em>+ <em>w + </em>w
Since <em>w</em> = 10, and p = 50..
<em />50 = <em>l </em>+ <em>l </em>+ 10 + 10
Simplify:<em>
</em>50<em> </em>= <em />2<em>l</em><em> </em>+ 20
Now let's solve:
Subtract 20 from each side.
30 = 2<em>l</em>
Divide by 2 on each side.
15 = <em>l</em>
Now that we know the length is 15, we can use this equation to find the area.
(<em>a</em> = area)
<em>a</em> = <em>wl
</em><em />Since w = 10, and l = 15...
<em>a </em>= 10 · 15
Solve:
a = 150
The answer is
150.
Hope this helped! If you have anymore questions or don't understand, please comment on my profile or DM me. :)