Nomor 19 bantuin ya... Sekalian caranya

ACB= 180-85=95
BAC= 180-100=80

ACB+BAC= 95+80
=175

ABC= 180-175= 5 (a)

<BCA = 180 - 85= 95°
<BAC = 180 -100 = 80°

<ABC = 180 - (80+95)
<ABC = 5°

jawaban A