jwb ya no 28 pke cara ya makasi yg udh jwb :)))))

(x +28) + (3x - 10) = 90
4x + 18 = 90
4x = 72
x = 18

besar penyiku ABD yaitu = sudut CBD
= 3x -10
= 54 -10
= 44 (B)

Mencari Nilai x:
(x + 28)° + (3x - 10)° = 90°
     x + 3x + 28° - 10° = 90°
                     4x + 18° = 90°
                             4x = 90° - 18°
                             4x = 72°
                               x = [tex] \frac{72}{4} [/tex]
                               x = 18°

Besar ∠ABD:
(18 + 28)° = 46°


Semoga Membantu :)