Step-by-step explanation:
Represent D and E as x because you don't know them
Now the sum of all these angles is 180
so,D+E+90(THE SIGN AT THE TOP)=180
D which is x the E which is also x
x+x+90=180
2x+90=180
2x=180-90
2x=90
[tex] \frac{2x}{2} = \frac{90}{2} [/tex]
cancel and you will get x as 45
therefore x is 45 degrees
