How do you write an inequality and solve given "a number decreased by 8 is less than 21"?

Question

4326 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-01-25T16:03:17

See the entire solution process below:

First, write the inequality.

Let's call the number we will be solving for #n#.

Therefore "a number decreased by 8" can be written as:

#n - 8#

"is less than 21" can be written as:

#< 21#

Putting this altogether gives:

#n - 8 < 21#

To solve for #n# add #color(red)(8)# to each side of the inequality which will solve for #n# while keeping the inequality balanced:

#n - 8 + color(red)(8) < 21 + color(red)(8)#

#n - 0 < 29#

#n < 29#