Q1) Answer should be 4X. The sum of the 3 biggest no. has to be less than or equal to 5X. So the answer could be 4X. Note they ask what it could be not what it is.

Q2) They have given the dimentions of 1 box = 15*12*10

Also total space the boxes occupy is 1.08 *10^6

So no. of boxes = Total Volume/ Volume of one box

Total cost = Total boxes * cost per unit = 150 (choice A)

Pls confirm if its correct or if I have made some mistake