Dividing by 2, we have S/2=lw+lh+wh. After that, we subtract lh from both sides to get S/2-lh=lw+wh. Next, we divide both sides by w to get (S/2)/w=l+h. Next, we divide by S/2 to get 1/w=(l+h)/(S/2). Lastly, we multiply by w and divide by (l+h)/(S/2) to get w=(S/2)/(l+h)
The question reminds you of all the tools you need:
It says ...
"Opposite angles are equal."
So the upper right angle is x+40 just like the bottom left,
and the bottom right angle is 3x+20 just like the upper left.
And it says ...
"The sum of all angles is 360°."
You know what each of the four angles is, so you can addum all up,
set the sum equal to 360, find out what number ' x ' is, and then
use that to find the size of every angle.
I split it into parts. The small rectangle sticking out is 2x3 which is a 6 and the big rectangle 4x8 which is 32. The triangle is 8x2/2 which is 8. 6+32+8 = 46
