Answer:
The size of the cardboard should be 
Step-by-step explanation:
The diagram for this question is shown on the first uploaded image
The volume of the box is 
The length and the Width of the card is
L = W = Z
From the question we are told that 7 in squares were cut from each corner
So the length and the width of the box would be
L = W = (Z - 7)
And the height would be H = 7 in
Mathematically the volume of the box can be represented as
So the Volume would be
Substituting values
=> 
Answer:
1627190
Step-by-step explanation:
(see attached for reference)
Given the number 1627187, we can see that the number in the tens place is the number 8.
How we round this depends on the number immediately to the right of this number. (i.e the digit in the ones place)
Case 1: If the digit in the ones place is less less than 5, then the number in the tens place remains the same and replace all the digits to its right with zeros
Case 2: If the digit in the ones places is 5 or greater, then we increase the digit in the tens place and replace all the digits to its right with zeros.
In our case, the digit in the ones places is 7, this greater than 5, hence according to Case 2 above, we increase the digit in the tens place by one (from 8 to 9) and replace all the digits to its right by zeros giving us:
1627190
12-7=5
10-5=5
is that what you where looking for?
Subtract original amount from new amount:
84 - 39 = 45
He bought 45 books.
