Răspuns:
<ABC+<BCA+<BAC=180°
<ABC=180°-2x-18
<BCA=180°-3x-24
<BAC=180°-4x+15
=>180°×3-2x-18-3x-24-4x+15=180°
-9x-42+15=-2×180°
-9×-27=-360
9×+27=360
9x=333
x=37
=>c)37
≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈
