Fifteen less than twice a number is the same as the number plus two. What is the number?

1 Answer
Dec 13, 2015

The number is 17.

Explanation:

In this type of word problem, the best strategy would be to break it up into parts, and then write it as an equation.

First, we look at the first part of the problem. The first part is "Fifteen less than twice a number".

Let us say that #n# represents the unknown number.

Twice a number is the same as two times the number, or #2n#, and fifteen less than #2n# is #2n - 15#.

Then we look at "is the same as" part of the word problem. This indicates that the two parts are equal. So we use an equal sign to represent it.

#2n - 15 =#

Finally, we look at the third part of the problem, which is "the number plus two". This is the same as #n + 2#.

If we were to write the entire word problem as an equation, the equation would be:

#2n - 15 = n + 2#

To solve for #n#, we would add 15 to both sides:

#2n = n + 17#

Then subtract #1n# from both sides:

#n = 17#

The number is 17.