Math puzzle

[amboy49]

Need help with granddaughters math problem (4th grade)

B has twice as much as A. C has three times as much as B. Together they have $171. What do each have ?

I know the answer is $19 - but what is the equation to figure this ? This seems to be an algebra problem. I got the answer by just plugging in numbers till it worked.

Thanks

 

[hopper68]

B=2A
C=3B
A+B+C=171

A+(2A)+(6A)=171

9A=171

A=19

 

[K_W]

B=2A
C=3B
A+B+C=171

A+(2A)+(6A)=171

9A=171

A=19

Wrong, that is old math. You must use your number lines.

 

[amboy49]

Thanks

 

[ws6guy]

Wrong, that is old math. You must use your number lines.

Please don't even get me start on number lines and such. Helping my second grader with his math infuriates me. This new way of teach math is just garbage. I'm sure I'm just going to love how they teach algebra. Luckily he seems to be a math wiz and very rarely asks for help.

 

[sugarcreekbrass]

I agree. I taught junior high math for 16 years. Between the state mandates and the fact that kids don't learn basic arithmetic in grade school, I couldn't do it anymore. The state keeps lowering the year when kids are supposed to master standards, but they still can't do simple mental math. Try teaching multi-step equations to 8th graders who can't add or subtract single digit numbers without a calculator.

 

[Double T]

Yep, I've been teaching my son the 4th grade standards from work via facetime....the way they are teaching is bull****.

I'm teaching him algebra the way I was taught. When I was just back in college (like 2 years ago), we used the same old tried and true way. The number lines, carrying wierdly, all that ****. Just makes it more confusing. Why change the way we have done something for close to forever?

 

[eldirector]

I've actually missed math problems on my daughter's homework, and even a test. In a few instances, I know with certainty that their answer choices were at LEAST ambiguous, if not flat out wrong. In another case, I could simply not understand the "story problem" well enough to answer. How they expect a 3rd grader to figure it out, I just don't know.

 

[BigRed]

Need help with granddaughters math problem (4th grade)

B has twice as much as A. C has three times as much as B. Together they have $171. What do each have ?

I know the answer is $19 - but what is the equation to figure this ? This seems to be an algebra problem. I got the answer by just plugging in numbers till it worked.

Thanks

I think the answer they are looking is "they all have equal amounts".

 

[Hohn]

B=2A
C=3B
A+B+C=171

A+(2A)+(6A)=171

9A=171

A=19

Until and unless we can train our kids how to intuitively solve problems in the way expertly modeled above, we are hosed.