The interior angles in a 4 sided polygon add up to 360°. You are already given two measurements of 90°, so you know that the lastvtwo angles sum to 360-90-90= 180°. Put this information into an equation and solve for x: (7x+27)°+(9x-7)°=180° 7x+27°+9x-7°=180° 16x+20°=180° 16x=160° x=10° Angle B is (7x+27)°, so just substitute x: B = 7(10)+27 B = 70+27 B = 97°
The place to start is with this fact: the sum (total) of all the angles of a quadrilateral is 360 degrees. You know the two right angles (90 degrees each), so
