Please help me ! I will give you a heart and Brainly , if you put a link I will report you !

Answer:
<4= 164
Step-by-step explanation:
the sum of any 2 angles of a triangle is equal to the exterior linear angle of the triangle
<1+<2=<4
8x+9+5x+12=14x+10
13x+21=14x+10
21=x+10
11=x
<4=14x+10
<4=14(11)+10
<4=154+10
<4= 164