To mail a package, the rate is x cents for the first pound and y cents for each additional pound, where x > y.
Cost of 3-pound package
We pay x cents for the first pound, and then y cents for each of the 2 additional pounds.
Total cost = x + y + y = x + 2y

Cost of 5-pound package
We pay x cents for the first pound, and then y cents for each of the 4 additional pounds.
Total cost = x + y + y + y + y = x + 4y

TOTAL cost = (x + 2y) + (x + 4y) = 2x + 6y
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Now let's see what happens when we COMBINE the two packages into an 8-pound package
Cost of 8-pound package
We pay x cents for the first pound, and then y cents for each of the 2 additional pounds.
Total cost = x + y + y + y + y + y + y + y = x + 7y
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Which method is cheaper, and how much money is saved?
We must determine which value is less: 2x + 6y or x + 7y
We're told that x > y. So let's use this information.

Take: 2x + 6y and rewrite it as (x + 6y) + x
Take: x + 7y and rewrite it as (x + 6y) + y
Both quantities have (x + 6y) in common. So those values are equal.
Since x > y, we know that (x + 6y) + y is less than (x + 6y) + x
In other words, x + 7y is less than 2x + 6y
In other words, the packages COMBINED is the cheaper option.

Determine the savings, we'll subtract the cheaper cost from the more expensive cost.
In other words: savings = (2x + 6y) - (x + 7y) = x - y (cents)

Answer: A

Cheers,
Brent

This problem could be hard because of the wording, but just get rid of the word "cents"

Just think about that x is greater than y, hence x=2 and y=1.

Then just create the two cases:

When they are combined 8 total pounds:

2 (which is x) + 1(which is y) multuplied by 7 left pounds = 2 + 7 = 9

Separeted:

3 (pounds)

2(x) + 1(y)(2 pounds left) = 2 + 2 = 4

5(pounds)

2(x) + 1(y)(4 pounds left) = 2 + 4 = 6

4 + 6 = 10

So you will save 1 by sending them in one package (10 - 9) --- 1

And, then just substitute, obvioulsy D and E are out.

A) Both saving (x-y) --- (2-1) --- 1

Using values, let x=4, y=2
First package rate weighing 3 pounds = 4+ 2*2 = 8
Second package rate weighing 5 pounds = 4 + 4*2 = 12
Total rate of individual packages = 8+12 = 20

Combined package rate weighing 8 pounds = 4 + 7*2 = 18
Difference = 2

Putting x=4 and y = 2 in the options

A is correct.