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, the sentence “If 15 is subtracted from three times a certain number, the result is 27.”can be translated into the following algebraic equation:

3n – 15 = 27

 

Solve this equation

3n – 15 =    27

     + 15 = + 15 Add 15 to both sides

3n + 0   =    42

3n         =    42

 

3n/3      =    42/3 Divide each side by 3

 n          =    14

 

Now we substitute the solution for 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 the original  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(3 X 14), the result is 27.

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

42 – 15 = 27

 

We have just solved a first degree equation.

 

(Note 1)

The source for the problem statement is:

“Intermediate Algebra  For College Students” by Jerome E. Kaufman

 


Close Window