Answer:
30 + 18x
Step-by-step explanation:
Dimensions of small rectangular package:
Area = 9x square units
Height = 5 units
Dimensions of large rectangular package:
Area = 6 square units
Height = (5 + 3x) units
Volume of large rectangular box = area × height
Volume of the large box = 6(5 + 3x) = 30 + 18x