Area of the base and the top :(4x7) + (4x7) = 56
Lateral area of the front & the back = (4x12) + (4x12) = 96
Lateral area of the right & left = (7x12) + (7x12) = 168
TOTAL AREA = 56+96+168 = 320
Volume = 4x7x12 = 336
RATIO AREA/VOLUME = 320/336 . Simplify by dividing numerator and denominator by 16. Final result: AREA/VOLUME = 20/21