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Question 471925: Complete the ordered pair for the equation y=-10x+18 (_, 78)
Found 2 solutions by karaoz, bucky:
Answer by karaoz(32)   (Show Source):
You can put this solution on YOUR website! The unstated assumption in the question is that the ordered pair is written as (x, y) and not (y, x).
With this assumption we can then see that by giving the ordered pair (_, 78), the author of the question wants us to understand that y = 78 and x is not known.
However, x can be found from the fact that y = 78 and the fact that the two variables are related through the equation:
y = -10x + 18.
Substituting y = 78 into the equation we can find the value of x.
78 = -10x + 18
Take away 18 from both sides of the equation (the purpose is to isolate x on one side).
78 - 18 = -10x + 18 - 18
Simplify.
60 = -10x,
which is the same as
-10x = 60
Divide the whole equation by -10 (the purpose is still the same: isolate a single x to be alone on one side of the equation)
-10x/(-10) = 60/(-10)
Simplify
x = -6
Solved.
The ordered pair is (-6, 78)
Answer by bucky(2189)  (Show Source):
You can put this solution on YOUR website! The ordered pair consists of a value for x along with its corresponding value of y such that when those two values are substituted into the equation the left side of the equation equals the right side.
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The equation you are given is:
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y = -10x + 18
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You are also told that the value of y in the ordered pair is 78. Substitute that value into the equation and solve for the corresponding value of x. Substituting 78 for y results in the equation becoming:
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78 = -10x + 18
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Get rid of the 18 on the right side by subtracting 18 from both sides and you have:
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60 = -10x
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Solve for x by dividing both sides by -10 and the result is:
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-6 = x
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So now you can say that the ordered pair that makes the equation true is (-6,78).
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You can check this by returning to the original equation of:
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y = -10x +18
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and substitute -6 for x and 78 for y to get:
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78 = -10*(-6) + 18
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Do the multiplication on the right side (the minus 10 times minus 6) to get:
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78 = 60 + 18
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And the addition on the right side results in:
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78 = 78
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This means that the ordered pair (-6, 78) makes the equation true (equal on both sides) and is therefore the answer you need.
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Hope this helps you to understand the problem.
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