How do you write an inequality and solve given "twice a number is more than the sum of that number and 9"?

1 Answer
Mar 12, 2017

Answer:

See the entire solution process below

Explanation:

First, let's call the number we are looking for #n#.

Now, we can write "twice a number" as #2n#

And, we can write "the sum of that number and 9" as #n + 9#

The first "is more than" so we can write the inequality as:

#2n > n + 9#

To solve, subtract #color(red)(n)# from each side of the inequality to find #n# while keeping the inequality balanced:

#2n - color(red)(n) > n - color(red)(n) + 9#

#2n - 1color(red)(n) > 0 + 9#

#(2 - 1)n > 9#

#1n > 9#

#n > 9#