Answer:
45 degrees
Explanation:
The 4 angles of a quadrilateral will add to 360.
We know 1 of them (angle B) is 90 degrees.
We can set up an equation to solve the others.
2x+3x+x+90 = 360
Now solve for x.
Start by combining the x terms together.
6x+90 = 360
6x = 360-90
6x = 270
(6x/6) = 270/6
x = 45 degrees
Check back to see if that makes sense and if the equation equals 360 when x is 45:
2x+3x+x+90 = 360
2(45)+3(45)+45+90=360.