Question

Barbie is thinking of a number. Twenty less than one-third of the number is 72. What is Barbie's number?

I know that this is an easy equation but I keep on ending up with 236 as my answer. Help? Please include work on the problem

Answer 1

`276`

Explanation:

Let the number be `x`

Then, `1/3x-20 = 72`

or, `1/3x = 72+20`

or, `1/3x = 92`

or, `x = 92xx3` = `276`

Answer 2

Let the number Barbie is thinking of be `x`

`x/3 -20 =72`

solve for `x`

Explanation:

`x/3 -20 = 72`

add 20 to each side

`x/3=92`

multiply both sides by 3

`x = 276`

Answer 3

`x=276`

Explanation:

All right. Let's write an equation.

`"Twenty less than one-third of the number is 72"`

Using `x` as the number, the sentence is equivalent to

`x/3-20=72`

We add 20 on both sides.

=>`x/3-20+20=72+20`

=>`x/3=92` We now multiply both sides by 3.

=>`(x/3)3=92*3`

=>`x=276`

That is our answer!

I think that you did something like this:

`x/3-20=72`

`x-20=216`

=>`x=236`

This would not be true because when you multiply both sides by 3, you would get:

`3(x/3-20)=72*3` Distribute.

=>`x-60=216`

=>`x=276`

We still get the same answer.

Answer 4

Barbie's number is `276`, see below:

Explanation:

`1/3*x-20=72`

`1/3*xcancel(-20+color(red)(20))=72+color(red)(20)`

`1/3*x=92`

`cancel(1/3)*x*cancel(color(red)(3))=92color(red)(*3)`

`x=276`