tolong dong nomor 3 jawab soalnya susah banget

Materi : prisma dan Limas
Kelas : 8 SMP

Panjang kerangka Limas = 4 (rusuk alas + rusuk tegak)
= 4 (13 + 17) cm
= 4 × 30 cm
= 120 cm

Sisa kawat = 261 cm - 120 cm = 141 cm

Panjang kerangka prisma ∆ = (3 × t) + 2(a + b + c)
141 = (3 × 25) + 2(5x + 4x + 2x)
141 = 75 + 22x
22x = 141 - 75
22x = 66
x = 66/22
x = 3

a = 5x = 5(3) = 15 cm
b = 4x = 4(3) = 12 cm
c = 2x = 2(3) = 6 cm