Answer:
1 package contain 80 sheets of paper.
If there is 5 packages, there will be 'x' sheets of paper.
We replace the sheets of paper with 'x', because the value of x is unknown.
Now we set up the equation:
Sheets 80 x
__________ _________ = _________, solve for x;
Packages 1 5
80/1 = x/5
*5 *5
400 = x