10th Dec 2009
How Would You Set Up This Algebraic Problem Solving Question?
Kacey and Starr found that if 3 times a number is decreased by 5 and this difference is doubled, the result is 14 less than twice the number. What is the number?
Please help, thanks.
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Tags: Difference, How, Kacey, number, result, Set, Starr, Up, Would, You
Let n be the number you’re looking for. Just write out what the problem says and when you get to “the result is” put an equals sign.
3 times a number = 3n
decreased by 5 = 3n – 5
double the difference = 2(3n – 5)
twice the number = 2n
14 less = 2n -14
so, 2(3n – 5) = 2n – 14
Now we solve the equation for n to find the number.
1) 2(3n – 5) = 2n – 14 {multiply the 2 across the parentheses}
2) 6n – 10 = 2n -14 {add 10 to both sides}
3) 6n = 2n – 4 {subtract 2n from both sides}
4) 4n = -4 {divide both sides by 4}
5) n = -1
That’s it!
the equation is: 2(3n-5) = 2n-14
6n-10 = 2n-14
4n = -4
n = -1 and this is the unswer