The triangles are similar and the angles are congruent to their counterpart.
Triangle TKM is similar to triangle DAJ. This mean angle T is congruent to angle D. Angle K is congruent to angle A and angle M is congruent to angle J.
Since triangle angles add to 180, and we know two of the angles, we can form an equation to find the third angle.
On both triangles :
Angle T and D add right angles as indicated by the square box. Right angles equal 90.
So we have: 90+30+x=180 120+x=180 Subtract 120 from each side to solve x and you end up with X= 60
