Homework help

[Mom loves Disney]

Here goes.

Brett made muffins for his grandmother, but he gave his friend Steve 1/8 of the muffins. Then Brett saw Dori and gave her 1/3 of what he had left. Then he saw Shelia and gave her 1/7 of what he had left. By the time he arrived at grandmother's house there were only 12 muffins left.

A: How many muffins did Brett make?
B: How many did each person get?

My son said he made 24 and Steve got 3, Dori got 7, and Shelia got 2.
(is he correct?)
Can somone please show me step by step how to do this because he has me all mixed up. I would really like to understand this!!! If you made it this far, THANKS.

 

[Piecey]

You use common denominators.
I'm pretty sure your son is right but it's been awhile since I've done math like this.


Steve got 1/8 of the original muffins.
Dori got 1/3 of 7/8. Common denominator means Dori got 1/3 of 21/24 (1/3 of 21= 7). So Dori got 7.
Go back and use the common denominator with Steve to get 3/24. So Steve gets 3.... etc.

 

[katiebelle21]

Your son is correct! I'll try to give an explanation:

Brett made muffins for his grandmother, but he gave his friend Steve 1/8 of the muffins. Then Brett saw Dori and gave her 1/3 of what he had left. Then he saw Shelia and gave her 1/7 of what he had left. By the time he arrived at grandmother's house there were only 12 muffins left.

Brett starts with 24. He gives 1/8 away, which is 3. (24 divided by 8=3) So Steve has 3.
Brett now has 21. He gives 1/3 away, which is 7. So Dori has 7.
Now Brett has 14. He gives 1/7 away, which is 2. Shelia gets two.
Now Brett has 12 left.

 

[Piecey]

Your son is correct! I'll try to give an explanation:

Brett made muffins for his grandmother, but he gave his friend Steve 1/8 of the muffins. Then Brett saw Dori and gave her 1/3 of what he had left. Then he saw Shelia and gave her 1/7 of what he had left. By the time he arrived at grandmother's house there were only 12 muffins left.

Brett starts with 24. He gives 1/8 away, which is 3. (24 divided by 8=3) So Steve has 3.
Brett now has 21. He gives 1/3 away, which is 7. So Dori has 7.
Now Brett has 14. He gives 1/7 away, which is 2. Shelia gets two.
Now Brett has 12 left.

You said it much better than I did!

 

[lovetoscrap]

Were the muffins Blueberry or Chocolate?

 

[FireDancer]

Here goes.

Brett made muffins for his grandmother, but he gave his friend Steve 1/8 of the muffins. Then Brett saw Dori and gave her 1/3 of what he had left. Then he saw Shelia and gave her 1/7 of what he had left. By the time he arrived at grandmother's house there were only 12 muffins left.

A: How many muffins did Brett make?
B: How many did each person get?

My son said he made 24 and Steve got 3, Dori got 7, and Shelia got 2.
(is he correct?)
Can somone please show me step by step how to do this because he has me all mixed up. I would really like to understand this!!! If you made it this far, THANKS.

I solved by using a set of linear equations solving for x. Brett made x muffins. He saw steve and gave him 1/8x muffins leaving him with y muffins. He then saw Dori and gave her 1/3y muffins leaving him with z muffins. He then saw Sheila and gave her 1/7z muffins leaving him with a. You know a=12

The system of linear equations becomes:

x-1/8x=y
y-1/3y=z
z-1/7z=a
a=12

When you solve the equation backwards you see that z=14, y=21, and x= 24 meaning he original made 24 muffins as x was the original amount.

You can then either use subtraction or multiplication by a fraction to determine how much each person got:
Steve got 1/8 * 24 = 3 leaving Brett with 21 (y)
Dori got 1/3 * 21 = 7 leaving Brett with 14 (z)
Sheila got 1/7 * 14 = 2 leaving Brett with 12 (a) which is what grandma got.

Sorry it took so long. Getting this from paper onto a computer through a keyboard was harder than the math.

This is also assuming the original amount was unknown because that was my interpretation of the question. If the original amount was known than skip the linear equations.

 

[damo]

I'll give it to you algebra-wise. Let x be the total number of muffins made.

Then Brett gives Steve x/8, leaving him with 7x/8
Then Brett gives Dori 1/3(7x/8) or 7x/24 leaving him with 7x/8 - 7x/24 or 14x/24 = 7x/12
Then Brett give Shiela 1/7(7x/12), leaving him with 7x/12 - 1/7(7x/12) = 6/7(7x/12) = x/2
Since he is left with 12 muffins, our last expression must equal 12
Solving gives x/2 = 12, so x=24

You can work backwards to figure out how many muffins each person got but substituting 24 in for x.

 

[Mom loves Disney]

Yes, the original amount was not known. You people rock!!! I get it now. THANKS.