one bundle contains 420 $20 bills. what would be the total value of 60 bundles

Question

I need help with this story problem for my daughter. Her dad and I can't figure it out. 

Answer 1

To change the units without changing the value, we use the multiplicative identity (that is, 1).  You may multiply any value by 1 and it remains the same.

 

In this problem:

  1 = (420 bills) / (1 bundle)              "one bundle contains 420 bills"

  1 = ($20) / (1 bill)                            "$20 bills"

 

We have:

     60 bundles

     (60 bundles) * 1

     (60 bundles) * ( ( 420 bills) / (1 bundle) ) * ( ($20) / (1 bill) )

     (60)*(420)*(20)   $             [note that bundles, bills cancel out]

     $ 504,000

 

60 bundles of $20 bills is worth $504,000.

Answer 2

My approach is to first find out the value of one bundle. We've been told: one bundle contains 420 $20 bills.

Let's write this as an equation, with x representing one bundle: x = 420 * $20
Doing this math, we find that one bundle is worth $8,400.

The next part is to find the value of 60 bunches, or 60 * x. This is as easy as $8400 * 60 = $504,000.

All put together, the math can be understood as (420 * $20) * 60.

Hope this helps! I'd be happy to give more examples or details if interested. Algebra has always been something I enjoy doing!