A triangle always equal 180.
The two marks indicate that 3x and the unlabeled corner is congruent to each other.
Let the unlabeled corned be another x.
Add everything and equal it to 180.
3x+x+x=180
Combine like terms.
5x=180
Divide by 5.
x=36
Substitute the x in 3x for 36.
3(36)=108
Then subtract that number from 180.
180-108=72
Divide the 72 by 2 so it can come out evenly. That’s 36.
Thus
3x=108
x=36
Unlabeled=36
Hope this helps.
