perhatikan gambar berikut ! nilai (a+8)°

(3a + 15) + (2a - 10) = 180.
5a - 5 = 180.
5a = 180 - 5.
5a = 175.
a = 175/5.
a = 35.

= a + 8.
= 35 + 8.
= 43°.