Answer:
m<4 = 52°
m<BFD = 98°
Step-by-step explanation:
m<1 = (3x)°
m<2 = (5x - 7)°
m<3 = (4x + 15)°
m<AFD = 128°
✔️Find m<4:
m<4 = 180° - m<AFD (angles on a straight line)
Substitute
m<4 = 180° - 128°
m<4 = 52°
✔️m<BFD = m<2 + m<3
Substitute
m<BFD = (5x - 7)° + (4x + 15)°
We need to find the value of x.
Create an equation to find x.
m<1 + m<2 + m<3 = m<AFD (angle addition postulate)
Substitute
3x + 5x - 7 + 4x + 15 = 128°
Add like terms and solve for x
12x + 8 = 128
12x + 8 - 8 = 128 - 8
12x = 120
12x/12 = 120/12
x = 10
m<BFD = (5x - 7)° + (4x + 15)°
Plug in the value of x
m<BFD = 5(10) - 7 + 4(10) + 15
m<BFD = 50 - 7 + 40 + 15
m<BFD = 98°
