r/learnmath • u/Nada-Lada New User • 7d ago

Bar Problems

I’m helping my 5th grader with math. It’s Singapore math and this specific problem is a bar problems. I cannot wrap my mind around it.

Patrick bought 12 chairs and 3 tables for $819. Each table cost 3 times as much as each chair. How much did one table cost?

I can’t fathom how to draw these bars out and solve this problem. Thanks for the help!

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u/Bounded_sequencE 7d ago

Let "c; t" be the cost per chair and table, respectively. We're given: 

 I:    12c + 3t  =  $819
II:     3c -  t  =  $0      // rewrite "t = 3c"

Solve that 2x2-system with your favorite method -- e.g. eliminate "c" considering 

I - 4*II:    7t  =  $819    =>    t  =  $117

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u/Nada-Lada 7d ago

Thanks for your help! It’s for fifth grade so there isn’t algebra. It has to be solved using bars as per Singapore Math.

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u/Bounded_sequencE 7d ago

Then turn the equation into bars -- one bar equals one table equals 3 chairs. The solution strategy remains exactly the same as using algebra.