Supplementary angles are angles that add up to 180 degrees.
180 = 3x + 4 + 8x + 11
Combine like terms.
180 = 11x + 15
Subtract 15 from both sides.
165 = 11x
Divide both sides by 11
15 = x
m<ABC = 3x + 4 = 3(15) + 4 = 45 + 4 = 49 degrees.
Answer: angle 7 = 80 degree and angle 8 = 100 degree
Answer:
As mentioned ABCD is a square
So <DEC is always 90 degree
1\8 is actually 0.125 so I hope this helps