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If (x, y) is a solution to the system of equations above, then what is the value of x - y?

A. 1/4

B. 1

C. 3

D. 18

If (x, y) is a solution to the system of equations above, then what is the value of-example-1

1 Answer

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1. The first step to solving this problem is to find the values of x and y. This can be done in a multitude of different ways, however I will go with the method of substitution.

Thus, the first thing we must do is write out both equations and rearrange one of them so that either x or y is the subject of the equation. Looking at the two equations, I can see that in the second equation this would be easier, and that we could also simplify the first equation a little further. Thus:

a) Collecting like terms to simplify equation 1:

4x + 3y = 14 - y

4x + 4y = 14 (Add y to both sides)

b) Rearranging equation 2 to make x the subject:

x - 5y = 2

x = 2 + 5y (Add 5y to both sides)

Now, we can substitute x = 2 + 5y into the first equation:

4x + 4y = 14

if x = 2 + 5y:

4(2 + 5y) + 4y = 14

8 + 20y + 4y = 14 (Expand 4(2 + 5y))

8 + 24y = 14 (Add 20y and 4y)

24y = 6 (Subtract 8 from both sides)

y = 1/4 (Divide both sides by 24)

Now that we know that y = 1/4, we can substitute this back into x = 2 + 5y:

x = 2 + 5y

if y = 1/4: x = 2 + 5(1/4)

x = 2 + 5/4

x = 13/4

2. So now we know that x = 13/4 and y = 1/4. Given these values, we can now solve x - y as such:

x - y = 13/4 - 1/4

= 12/4

= 3

Thus, the value of x - y is 3 (answer C).

User Kevin Sabbe
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