SOLUTION: When 18 is subtracted from four times a certain number, the result is 5/2 the original number. What is the number?

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Question 550551: When 18 is subtracted from four times a certain number, the result is 5/2 the original number. What is the number?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
"When 18 is subtracted from four times a certain number, the result is 5/2 the original number. " means that we have the equation 4n-18=%285%2F2%29n. Let's solve this equation for n.


4n-18=%285%2F2%29n Start with the given equation.


2%284n-18%29=2%28%285%2Fcross%282%29%29n%29 Multiply both sides by the LCD 2 to clear any fractions.


8n-36=5n Distribute and multiply.


8n=5n%2B36 Add 36 to both sides.


8n-5n=36 Subtract 5n from both sides.


3n=36 Combine like terms on the left side.


n=%2836%29%2F%283%29 Divide both sides by 3 to isolate n.


n=12 Reduce.


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Answer:

So the solution is n=12


So the unknown number is 12