Find the value of x.

It's a right angle. One of the angles says (3x) degree other side says (4x-1) degree

x=13

Step-by-step explanation:

The sum of the angles of a triangle add to 180 degrees

3x + 4x-1 + 90 = 180

Combine like terms

7x + 89 = 180

Subtract 89 from each side

7x + 89-89=180-89

7x = 91

Divide each side by 7

7x/7 = 91/7

x = 13