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

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

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Jan 30, 2018

Answer:

#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.

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Aviv S. Share
Jan 29, 2018

Answer:

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#

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Jan 30, 2018

Answer:

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#

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MJ Share
Jan 29, 2018

Answer:

#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#

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