Rumus volume balok :

V = plt

Rumus panjang rusuk balok :

4 (p + l + t)

Panjang = (3x - 1) cm

Tinggi = (x + 3) cm

Lebar = (2x - 3) cm

Panjang rusuk balok = 116

Banyak panjang rusuk kubus = 4(p + l + t)

116 = 4((3x - 1) + (2x - 3) + (x + 3))

116 = 4(3x - 1) + 4(2x - 3) + 4(x + 3)

116 = (12x - 4) + (8x - 12) + (4x + 12)

116 = (12 + 8 + 4)x + (-4 - 12 + 12)

116 = 24x - 4

116 + 4 = 24x

¹¹⁶ ⁺ ⁴/₂₄ = x

5 = x

Substitusi nilai x kedalam panjang, lebar, dan tinggi balok :

P = (3x - 1)

  = 3(5) - 1

  = 14

T = (x + 3)

   = 5 + 3

   = 8

L = (2x - 3)

  = 2(5) - 3

 = 7

Volume = plt

             = 14(8)(7)

             = 784 cm³