See those lines that are pependicular meanins that those lines are same legnth in triangle, if 2 sides are same measure legnth then the angles oposite those sides are same measure
therefor top right and top left angle is 42
remember that vertical angles are congruent
remmeber all angles ad to 180 in a triangle
so therefor look at top triangle top right angle is 42 top left is 42 bottom must be x total is 180 so 42+42+x=180 84+x=180 minus 84 fromboth sides x=96
