Original measurements:
L = 4; W = 6; H = 7
surface area = 2(LW + LH + HW)
surface area = 2(4 * 6 + 4 * 7 + 6 * 7)
surface area = 2(24 + 28 + 42)
surface area = 2(94)
surface area = 188
Doubled measurements:
L = 8; W = 12; H = 14
surface area = 2(LW + LH + HW)
surface area = 2(8 * 12 + 8 * 14 + 12 * 14)
surface area = 2(96 + 112 + 168)
surface area = 2(376)
surface area = 752
The surface area was 188 square inches and it became 752 square inches.
752/188 = 4
As the side lengths increased by a factor of 2, the surface area increased by a factor of 4.