Step: 1
Let w be the weight of the second box.
Step: 2
285 + w = 666
[Write a linear equation for the total weight of the two boxes.]
Step: 3
285 + w - 285 = 666 - 285
[Subtract 285 from each side.]
Step: 4
Step: 5
So, the weight of the second box, w is 381 lb.
Correct Answer is : 381 lb