Respuesta :

Answer:

x = 21

Explanation:

The two remaining angles must add to 90 degrees since a triangle adds to 180

3x+6 +x = 90

4x+6 =90

4x = 90-6

4x = 84

Divide by 4

4x/4 = 84/4

x = 21

The answer is 21 which is A
ACCESS MORE