10 points if you solve this one problem.

150

Step-by-step explanation:

The exterior angle is equal to the sum of the opposite interior angles

<1 + <2 = <3

3x+11 + 3x+19 = 7x+10

Combine like terms

6x+30 = 7x+10

Subtract 6x from each side

6x -6x+30 = 7x-6x+10

30 = x+10

Subtract 10 from each side

30-10 = x+10-10

20 =x

We need to find angle 3

<3 = 7x+10

    = 7(20)+10

    = 140+10

    = 150

first, you divide the triangle in two, tô form a retangle triangle. after, using pythagoream theorem:

18^2 = 14^2 + (x/2)^2

(x^2/4) + 196 = 324

x^2/4 = 324 - 196

x^2/4 = 128

x^2 = 512

x = √512

x = √2^9

x = 16√2 cm

i hope i you.

b

step-by-step explanation: