Math Is Easy - Use Algebra To Solve Word Problem 4!

If 15 is subtracted from three times a certain number,the result is 27. Find the number. (Note 1)

If we let n represent the number to be found, thesentence If 15 is subtracted from three times a certain number, the resultis 27.can be translated into the following algebraic equation:

3n15 = 27

Solve this equation

3n15 = 27

+ 15= + 15 Add 15 to bothsides

3n + 0 =42

3n = 42

3n/3 = 42/3 Divideeach side by 3

n = 14

Now we substitute the solutionfor n into the original equation to see if it works.

3n 15 =27

3(14) 15 = 27

42 15 =27

27= 27

We must also see if the solution works in theoriginal problem statement.

If 15 is subtracted from three times a certain number,the result is 27.

If 15 is subtracted from three times a certain number(3X 14), the result is 27.

If 15 is subtracted from 42, the result is 27.

4215 = 27

We have just solved a first degree equation.

(Note1)

The source for the problem statement is:

Intermediate AlgebraFor College Students by Jerome E. Kaufman


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