Answer:
To determine the number of sheets of cardboard in a stack, we need to use the information given in the problem.
We know that each sheet of cardboard is 1 inch thick, and 16 sheets are stacked on top of each other in packages. The height of each stack is 21 inches.
Using the model of a ruler, we can divide the height of the stack (21 inches) by the thickness of each sheet (1 inch) to find the number of sheets in the stack.
21 ÷ 1 = 21
So, there are 21 sheets of cardboard in a stack.
To write an expression that can be used to determine the number of sheets of cardboard in a stack, we can use:
Number of sheets = height of stack ÷ thickness of each sheet
Or, substituting the given values: Number of sheets = 21 ÷ 1 = 21
This expression is simply a representation of the model we used earlier. It shows that we can determine the number of sheets in a stack by dividing the height of the stack by the thickness of each sheet. In this case, the expression yields the same result as the model, which is 21 sheets.