Please Help ASAP I dont understand this

To find m<3, we can use the angle sum of triangles, in which the addition all angles in a triangle must be equal to 180°.
In this case:
m<3 +52°+29° = 180°
m<3 + 81° = 180°
m<3 = 180°-81°
m<3 = 99°
To find m<4, we can use adjacent angles on a straight line, where the addition of angles on a straight line must be 180°.
In this case:
m<4 + 99° = 180°
m<4 = 180°-99°
m<4 = 81°
Therefore m<3 is 99° while m<4 is 81°.
Hope it helps!