Answer:
Explanation:
a) The two red lines indicate that EF and DF are equal length
EF = DF
2y + 5 = 21
2y = 16
y = 8
b) The angle marks indicate that D and E are equal. all angles of a triangle add up to 180 degrees
D = E
D + E + F = 180
4x + 4x + 2x = 180
10x = 180
x = 18
c) Knowing that x = 18, solve angle F
F = 2x
F = 2(18)
F = 36
d) Angle D and E are equal. Angle E equals 4x and x = 18
D = E
D = 4x
D = 4(18)
D = 72