21 + (-21) + (-4) please help me out with this question

-4

Step-by-step explanation:

Adding 21 and -21 cancel each other out so you're left with -4

idk what the answer is but for the points

step-by-step explanation:

the first one and the second one that's the answer

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐