10 Find the value of x.
11
9.
10.
12.
*°
910
1189
11.
12.
4x - 15)
(x - 30)
115°
145°

9) x = 89°

10) x = 118°

11) x = 145°

12) x = 40°

Step-by-step explanation:

9) 180-91 = 89

10) x = 118° because it is alternate interior to 118

11) x-30 = 115,     x = 145

12) 4x-15 = 145,    4x = 160,   x = 40

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.

a

step-by-step explanation: