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Question 436105: Five times the sum of some number plus 3 is equal to 7 times the number minus 3
Answer by marilynh(7)   (Show Source):
You can put this solution on YOUR website! First we have to set up an equation to solve:
Let "some number" = x
therefore "the sum of some number plus 3" = x + 3
and "five times the sum of some number plus 3" = 5 ( x + 3)
So we have found one side of the equation is 5 ( x + 3)
We are told this is equal to 7 times the number minus 3:
"seven time the number" = 7x
therefore "7 times the number minus 3" = 7x - 3
Now set the two sides of the equation equal to each other and solve for x:
5 (x + 3) = 7x - 3
5x + 15 = 7x - 3
15 = 7x - 3 - 5x
15 = 2x - 3
15 + 3 = 2x
18 = 2x
9 = x
"some number" = 9
Check your answer by substituting 18 for x in the equation:
5 (9 + 3) = 7(9) - 3
5 (12) = 63 - 3
60 = 60
Since multiplication comes before subtraction "7 times the number minus 3" means 7x - 3, not 7(x-3)
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