Answer:
12
Step-by-step explanation:
These triangles are similar using the AA theroem. This means there sides are in corresponding proportion.
Side AR and Side TE are corresponding. Use this proportion.

This side the triangle SAR side lengths are 3/4 of side lengths of triangle SET.
We know that RS+ST=21
And that RS=3/4(ST).


x=12.
Side ST is 12
The area of a rectangle is length times width or base times height
so 5 times 2x-3
if you multiply them together 5(2x-3) you would get 10x-15
there is no value of x
so the area would be 10x-15ft^2
7-12 is like a negative number so it will be -5. And 13-18 would be -5 also.
Hi there!
Using the formula - n-2*180 -, we know that the interior angles of a pentagon add up to 540. We can use the values we're given and add them together and set them all equal to 540, then solve.
WORK:
540 = 204 + 12x
336 = 12x
x = 28
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!