Respuesta :

Answer:

x=21

Step-by-step explanation:

The sum of the angles of a triangle is 180

100 + 3x + x-4= 180

Combine like terms

100 -4  + 3x+x = 180

96+4x = 180

Sutract 96 from each side

96-96 +4x = 180-96

4x =84

Divide each side by 4

4x/4 = 84/4

x = 21