you have to build an equation to find the answer,
angles in a straight line add upto 180°
so your equation would be,
12x+30°=180°
-30 -30
=12x=150°
÷12 ÷12
=x=12.5°
now find the measures of the angles by using 12.5 as x.
angle EAF= 2x
=2×12.5
=25° degrees
angle DAE= 4x
=4×12.5
=50°degrees
angle CAD=6x
=6×12.5
=75°degrees
check,
30+25+50+75=180°degrees
hope this helps.......
