12. Diketahui sudut-sudut berikut.

Jawaban:

27⁰ (tidak ada di pilihan abcd nya)

Penjelasan dengan langkah-langkah:

2a – 6 = 40⁰

2a⁰ = 40⁰ + 6⁰

2a⁰ = 46⁰

a⁰ = 46⁰ : 2

a⁰ = 23⁰

3b⁰ + 14⁰ + 112⁰ = 180⁰

3b⁰ = 180⁰ – 14⁰ – 112⁰

3b⁰ = 54⁰

b⁰ = 54⁰ : 3

b⁰ = 18⁰

40⁰ + 3b⁰ + 14⁰ + 3c⁰ = 180⁰

40⁰ + 3•18⁰ + 14⁰ + 3c⁰ = 180⁰

108⁰ + 3c⁰ = 180⁰

3c⁰ = 180⁰ – 108⁰

3c⁰ = 72⁰

c⁰ = 72⁰ : 3

c⁰ = 24⁰

3c⁰ + 2d⁰ + 32⁰ = 180⁰

3•24⁰ + 2d⁰ + 32⁰ = 180⁰

72⁰ + 32⁰ + 2d⁰ = 180⁰

2d⁰ = 180⁰ – 72⁰ – 32⁰

2d⁰ = 76⁰

d⁰ = 76⁰ : 2

d⁰ = 38⁰

a + b + c – d

= 23⁰ + 18⁰ + 24⁰ – 38⁰

= 27⁰