(A) For x representing the cost of one of Tanya's items, her total purchase cost 5x. The cost of one of Tony's items is then (x-1.75) and the total of Tony's purchase is 6(x-1.75). The problem statement tells us these are equal values. Your equation is ...
... 5x = 6(x -1.75)
(B) Subtract 5x, simplify and add the opposite of the constant.
... 5x -5x = 6x -6·1.75 -5x
... 0 = x -10.50
... 10.50 = x
(C) 5x = 5·10.50 = 52.50
... 6(x -1.75) = 6·8.75 = 52.50 . . . . . the two purchases are the same value
(D) The individual cost of Tanya's iterms was $10.50. The individual cost of Tony's items was $8.75.
 
        
             
        
        
        
Knowing the volume of a 3-D shape is extremely when deciding what materials to use and how much of them to use.  When you know the volume of the different designs is helpful when deciding which material costs less to use but still meets requirements. For example, if you were trying to decide what material to fill your product with, and say the volume of your product is 36^3. You narrow things down to two products, one costing $54 to fill the entire thing. The other costing $60. Because you have the volume, it will be easy to decide which is better based off of the price per square inch. If you didn't have the volume. You would have to make an estimate and potentially make a bad business decision.   
Hope this helps! I apologize for my long response
        
             
        
        
        
Answer:
   more than 1100
Step-by-step explanation:
The contribution margin for each package sold is ...
   $6.50 -3.00 = $3.50
The number of packages that must be sold to cover fixed costs is ...
   3.50n > 3850
   n > 1100 . . . . . . . divide by 3.50
The company will generate a profit if more than 1100 packages are produced and sold each week.
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<em>Additional comment</em>
If exactly 1100 packages are sold, then costs are covered, but profit is 0. In order for profit to be positive, more than 1100 packages must be sold.