no.17 pada gambar diatas, nilai A + b= ... pake cara yaa..

105+3b = 180
3b = 180-105
3b = 75
b = 75/3
b = 25

3b = 5a (karena luar bersebrangan)
75 = 5a
a = 75/5
a = 15

a+b = 25 + 15
= 40

<105° dan <5a saling berpelurus, maka:
➡105° + 5a = 180° ➡ 5a = 180° - 105° ➡ 5a = 75° ➡ a = 75/5 ➡ a = 15°
<5a bertolak belakang dengan <3b, jadi:
➡5a = 3b ➡5(15) = 3b ➡ 75° = 3b ➡ b = 75/3 ➡ b = 25°
JADI, a + b = 15 + 25 = 40.. C.
semoga membantu (^.^)
tanda < dibaca sudut