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## #1 2013-06-04 02:32:06

ran
Novice

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### coins problem

Hi hopefully you guys can help me with this problem sum.

there are 45 coins in the piggy bank.

total amount is \$21.90

there are 7 \$1 coins in the piggy bank.

how many \$0.50 and \$0.20 coins are there in the piggy bank?

## #2 2013-06-04 04:09:20

bob bundy
Moderator

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### Re: coins problem

hi ran,

Welcome to the forum.

I've made two equations from this information and tried to solve the problem.  But the number of \$0.50 coins has come out as a fraction so either I've made a silly error or the information has a typo.  Have a look and see if you can sort it out;  the method should work.

First some letters for the number of coins.  I'm from the UK so I couldn't remember what you call those coins so for \$0.50 I'm using H and for \$0.20 I'm using F.

First equation based on number of coins

Second based on value of coins

Multiply the first by 2 and subtract the result from the second

Now if 73 was in the 3x table that would give H and F would quickly follow.  But you cannot have H not a whole number so I'm stuck.

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

## #3 2013-06-04 20:55:35

bobbym
Administrator

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### Re: coins problem

Hi;

There are no integer solutions to that problem.

I think the problem is a typo. Now  total amount is \$21.80 has a solution.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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