# Word problem involving currency...

• May 12th 2012, 06:43 AM
Builderjay2011
Word problem involving currency...

"A person changed \$200 into five- and ten- dollar bills. The person then had 28 bills in all. How many ten-dollar bills were there? What was the value of the five-dollar bills?"
• May 12th 2012, 06:47 AM
skeeter
Re: Word problem involving currency...
Quote:

Originally Posted by Builderjay2011

"A person changed \$200 into five- and ten- dollar bills. The person then had 28 bills in all. How many ten-dollar bills were there? What was the value of the five-dollar bills?"

f = number of \$5 bills

t = number of \$10 bills

solve the system of equations ...

f + t = 28

5f + 10t = 200
• May 12th 2012, 06:56 AM
Builderjay2011
Re: Word problem involving currency...
Sorry I do not understand.
• May 12th 2012, 07:05 AM
skeeter
Re: Word problem involving currency...
Quote:

Originally Posted by Builderjay2011
Sorry I do not understand.

what do you not understand? the meaning of each the equation and how they came about, or how to solve them?

what methods for solving systems of equations have you already learned?

you have to help out here, jay ... hard to read minds over cyberspace.
• May 12th 2012, 07:22 AM
Builderjay2011
Re: Word problem involving currency...
Does this make any sense? My teacher showed me this set-up which was totally different from yours.

Let 5f = number of five dollar bills
Let 10(28-f) = number of ten-dollar bills

200 = 5f + 10(28-f)
200 = 5f + 280-10f
200 - 280 = 5f - 10f
-80 = -5f

f = 16 number of five-dollar bills
28 - 16 = 12 number of ten-dollar bills
\$120.00 value of ten-dollar bills
\$80.00 value of five-dollar bills
• May 12th 2012, 08:59 AM
skeeter
Re: Word problem involving currency...
Quote:

Originally Posted by Builderjay2011
Does this make any sense? My teacher showed me this set-up which was totally different from yours.

Let 5f = number of five dollar bills
Let 10(28-f) = number of ten-dollar bills

200 = 5f + 10(28-f)
200 = 5f + 280-10f
200 - 280 = 5f - 10f
-80 = -5f

f = 16 number of five-dollar bills
28 - 16 = 12 number of ten-dollar bills
\$120.00 value of ten-dollar bills
\$80.00 value of five-dollar bills

5f is the amount of money the number of 5 dollar bills are worth

if f + t = 28

then t = 28-f = the number of \$10 bills

the amount of money in \$5 bills + the amount of money in \$10 bills = total money

5t + 10(28-f) = 200
• May 12th 2012, 09:04 AM
Wilmer
Re: Word problem involving currency...
Quote:

Originally Posted by Builderjay2011
Does this make any sense? My teacher showed me this set-up which was totally different from yours.

Let 5f = number of five dollar bills
Let 10(28-f) = number of ten-dollar bills

200 = 5f + 10(28-f)
200 = 5f + 280-10f
200 - 280 = 5f - 10f
-80 = -5f

f = 16 number of five-dollar bills
28 - 16 = 12 number of ten-dollar bills
\$120.00 value of ten-dollar bills
\$80.00 value of five-dollar bills

If that's EXACTLY what your teacher showed, then your teacher needs further training!

"Let 5f = number of five dollar bills": that' s not the number of \$5 bills, it's the VALUE of the \$5 bills.

Did your teacher not show this way:
Let f = number of \$5 bills; then 28-f = number of \$10 bills?
Then proceeded to:
5f + 10(28 - f) = 200
?????
• May 12th 2012, 12:01 PM
bjhopper
Re: Word problem involving currency...
In problems like this one it is usually easier to write an equation in one unknown
• May 12th 2012, 02:42 PM
Wilmer
Re: Word problem involving currency...
Quote:

Originally Posted by bjhopper
In problems like this one it is usually easier to write an equation in one unknown

I'd say "always easier" BJ !