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 By: lisatang (offline)  Wednesday, May 09 2012 @ 04:59 AM CDT (Read 1962 times)
lisatang

Amy and Benny had \$1628.25. When Amy spent 3/4 of her money and Benny spent 3/5 of his money, they then had the same amount of money left.
How much money did Benny have at first?

Junior

Registered: 01/26/12
Posts: 19

 By: ivylyelaykian (offline)  Wednesday, May 09 2012 @ 06:56 AM CDT
ivylyelaykian

Amy

Spent = 3u x 2 = 6u

Left = 1u x 2 = 2u
\

total = 8u

Benny

Spent = 3u

Left = 2u

Total = 5u

1) 8u + 5u = 13u 2)13u = \$1628.25 3) 1u =\$1628.25 divide by 13 = \$125.25 4)5u= \$125.25 x 5 = \$626.25

Newbie

Registered: 02/21/11
Posts: 5

 By: lisatang (offline)  Wednesday, May 09 2012 @ 11:41 PM CDT
lisatang

Thanks

But I don't quite get why amy x 2?

Lisa

Junior

Registered: 01/26/12
Posts: 19

 By: echeewh (offline)  Thursday, May 10 2012 @ 01:04 AM CDT
echeewh

Hey Lisa,

If you use Work Backwards technique, you can understand why you need to split ( or multiply ) the 4p of A at first. Here goes ...

Start drawing model from <After>

<After>

A |-----|
B |-----|

<Process>
This is after A spent 3/4 of her money and after B spent 3/5 of his money. Hence, the remaining money will consist of 1p of A and 2u of B as follows:

A |-----|
B |--|--|

Working backwards, we can derive the <Before> model as follows: A will have 4p; B will have 5u. Since the 1p of A contains equal qty as 2u of B, we can split each of the 1p of A into 2u each.

<Before>

A |--|--||--|--||--|--||--|--|
B |--|--||--|--||--|

In total, A + B = 13u.

========================================

Trust the above clarifies.

Cheers,
Edward

Active Member

Registered: 04/21/11
Posts: 627

 By: lisatang (offline)  Friday, May 11 2012 @ 02:57 AM CDT
lisatang

Thanks Edward. I ve got a clearer picture now.

Junior

Registered: 01/26/12
Posts: 19

 By: MathIzzzFun (offline)  Saturday, May 12 2012 @ 10:12 AM CDT
MathIzzzFun

Quote by: lisatang

Amy and Benny had \$1628.25. When Amy spent 3/4 of her money and Benny spent 3/5 of his money, they then had the same amount of money left.
How much money did Benny have at first?

Hi

use the "equalizing numerators" concept....

1/4 of Amy's money = 2/5 of Benny's money
2/8 of Amy's money = 2/5 of Benny's money
--> once the numerators are equalized, the denominators will be the respective shares,

Amy's money --> 8 units
Benny's money --> 5 units
Total --> 13 units -- \$ 1628.25

Benny's money = 5/13 x \$ 1628.25 = \$625.25

cheers.

Chatty

Registered: 04/02/10
Posts: 36

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