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 P4 math question
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By: khtay01 (offline)  Tuesday, May 01 2012 @ 03:04 AM CDT (Read 1535 times)  

Hi, can any pro help me on this question?

A has 512 blue & white button. After she gives away 3/4 of the white buttons, thenumber of white buttons left is 3/7 of the total number of buttons left. How many blue buttons does she have?

Thanks in advance for the help

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By: echeewh (offline)  Tuesday, May 01 2012 @ 09:12 PM CDT  

Hi there,

Following pls find worked solution:

W = 3/7
B = 4/7
W = 3u
B = 4u

< Using Work Backwards technique >

Since 3/4 W given away, we have ...

1/4 W (at first) --> 3u
4/4 W (at first) --> 12u

Number of units (u) for B remains unchanged Before and After.

Hence ...

W = 12u
B = 4u

Total (at first) = 16u --> 512
1u --> 32
B (at first) = 4u --> 4 x 32 = 128


Trust this helps.


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