The answer is 40° i will tell you how, Total angle sum of any triangle is 180° ∠A + ∠B + ∠E = 180° 70° + 80° + ∠E = 180° solve for ∠E ∠E = 30° Now solve use ∠BDE, ∠B + ∠D + ∠E = 180° 20° + 90° + 30° + x = 180° (in triangle DEB, ∠E = 30 + x ) (∠D is 90°) solve for x there fore, x = 40°
