3x(3x-2y)
you have to find a common factor between the two numbers. in this case it's three, so you just divide each number by three.
4, there are 4 equal angles
The most important thing that you have to know is that all angles in a triangle equals 180°
Answer:
DEC+DEF=180
DEC=180-116
DEC=64°
in triangle DCE
angle D+angle C+angle E=180
7y+6+4y+64=180
11y+70=180
11y=180-70
11y=110
y=110/11
y=10°
angle C=4y
=4(10)
=40°