Tolong kasih tau jawaban nomer 15,16 dan 17 pake cara ya

15. d1 × d2 × 1/2 = Luas
(3x + 1) × 12 × 1/2 = 96
(3x + 1) × 6 = 96
18x + 6 = 96
18x = 96 – 6
x = 90÷18
x = 5 (B)
16. d1 × d2 × 1/2 = Luas
18 × d2 × 1/2 = 216
9 × d2 = 216
d2 = 24 (C)
17. Luas segitiga = a × t × 1/2
56 = a × 7 × 1/2
56 × 2 = a × 7
112 ÷ 7 = a
16 = a

Luas layang-layang = d1 × d2 × 1/2
= 19 × 16 × 1/2
= 19 × 8
= 152 (C)
*maaf kalau salah